Well, it's official. I am PLUSSED. Wooo! They're not officially allowing people to invite anyone they want yet (I got the same message Deo, thought I could invite that way but no). BUT I do believe I've found a loop hole that lets me invite as many people as I want (until they close it, heh). So PM me if you want an invite.
What's that? You want to know what I think of Google+ so far? It rocks! Yes, there are some rough edges, yes some things don't work all of the time. But the things they are doing are either an improvement over Facebook (Circles), a totally new and potentially interesting feature (Sparks), or something Facebook doesn't have and may potentially be a "big deal" (Hangouts).
There are 4 main tabs/buttons to the primary UI. First is Home, this is basically like FB's home, including the stream of what your circles are sharing (like FB's "wall", of course), as well as controls and tools like stream selection, Spark links, Chat, Hangout, Contact Suggestions (suggestions from inside your own contacts as far as I can tell, but maybe later like FB's "do you know this person?"), and a people search bar.
Next is photos, which get top billing as one of these 4 buttons. Here you see photos from your circles (they also seem to show up in the Streams), photos from your phone, photos *of* you (face tagging is of course available, with one critical difference: you can control who is allowed to tag you without explicit confirmation), and "your albums" which are your Picasa albums. Google has a nice photo system in Picasa, so this is a great thing to get integrated. They've come up with a decent UI for browsing photos too, although sharing settings are not entirely clear yet (there's no explicit "share this photo" that I can see, although you can share whole albums; but if you make a comment on a photo it posts the photo and comment to your wall, so it's basically sharing it). You can also upload new photos. The photo viewing and commenting experience is definitely an improvement over FB (unsurprisingly as Picasa has been around for ages and is fairly mature).
Then there is a Profile link/tab. This kind of surprised me. My profile is actually somewhat barren at present. It shows my photo and my activity stream, like looking at your own profile and wall on FB, and there are additional tabs for About, Photos, Videos, +1's, and Buzz. This is in fact the only place I have seen Buzz, and it's interesting that it's still around and being semi-integrated into G+. But I would expect it to be a major tab/button up top if they actually intended to keep it. Otherwise one wonders how it differs from +1 and posts to the Stream(s). A nice touch is you can click on a button to easily and quickly view your profile as *anyone* in your contact list or as a general anonymous web surfer, so you can check to make sure your privacy settings are working very fast. Also nothing (or almost nothing) appears to be public by default, i.e. I click to view as the public web and nothing shows up in my Stream. When you click to Edit your profile, you just point and click on any part of your profile to edit it, including adding photos, links, places you've lived, personal description, etc, etc.
Last but not least is the Circles button/tab. Circles are exactly what you've heard, they're groups you can use to categorize your friends and enable sharing of specific content with specific groups extremely easily (or, seen the other way, they enable you to easily *avoid* sharing content with specific groups, e.g. the general public). They've made the Circle-making UI fun and this helps a lot in wanting to make your circles. It's also powerful, you can multi-select, drag-select, etc. so you can easily deal with hundreds of contacts, and it's all drag-and-drop with nifty animations. This functionality is definitely a big step over Facebook (and yes I've tried FB's "Groups" system). You can add people to multiple Circles, share with 1 or multiple circles, all your circles, or the public. It's a nicely flexible system that is also easy and fun to use. This to me is a big win. I know it's not as important to many other people as it is to me, but this is a "killer feature" that I have been waiting and wishing for. Once nice touch is you can easily control people's Circle membership from almost anywhere you see their profile pic (e.g. hover over a pic of "Joe" on a post he made to your Stream and you get a pop-up allowing you to add or remove him from your Circles). Little things like that set the UI apart.
Unsurprisingly the Home area seems to be where you'd hang out the most, just like Facebook. On Home are two things that also deserve some description. First there's Sparks, which I think is probably the least impressive and interesting feature, but still has some potential. This is basically like a topic-driven web link discovery system. You enter some key words and it finds you content based on them. This is not like a regular Google search, I'm not sure what they're doing, but it seems much more culled than that. I think how recent a result is plays heavily into whether it will be shown. Better than a simple search though is that you can save this to your "Spark List" and it will continually update you on new info for that area of interest. Naturally you can easily click to share anything in your Sparks. Like I said it's not too exciting, lots of other services already do similar stuff and probably do it better, but if they continue to flesh it out it could make the G+ home page even stickier by making it a real dashboard not only for all the info on your friend's activities, but also *all* your interests around the web.
Then there's Hangouts. This one seems like a possible game changer. It's not revolutionary in basic function, but its integration with a social network just may be. Basically it's "just" group video chat. It works through Google's existing Google Chat system that has included video for years. Only now it allows multiple people, and it has a pretty slick system for keeping focus on whomever is talking, or letting you choose focus, or selectively mute people. One cool feature is that it allows you to watch YouTube videos "together" (simultaneously), so you can get a fun shared experience. It's actually pretty novel, believe it or not, though it's not necessarily amazing or something you're likely to use a lot in the long run (though some people who like watching YT videos with friends more than I do might love it). It also includes text chat, and lets you invite more people in very easily. Incidentally inviting people to Hangout is the way I've found to get anyone a G+ invite. Shh, keep it under your hat!
When you start a Hangout it posts to your stream and others can easily join. It also documents who was part of the Hangout ("Oshyan was Hanging out with Katy and Corey").
I jumped into a Hangout with a friend who was in the room and another friend half way across the country who happened to just call me and I was able to send him an invite. I really just wanted to test the functionality but it ended up being really fun and cool. It's a well-done system and, despite the occasional glitch, works nicely. It has a simple, clean UI and just enough features to be exciting and useful, while not being overwhelming.
So you're probably wondering why I think Hangouts could be a "game changer". Well, so far group video chat hasn't really been easily or widely available. Skype, for example, just introduced it recently and they *charge* for the feature. I'm sure we all know someone who uses Skype or even Google Chat to keep in touch with friends and - especially - relatives in distant places. It's becoming almost cliche for grandma and grandpa to video chat with their little niece or nephew on the opposite coast. But until now it's just been one person at a time. Now imagine grandpa and grandpa being able to get on to chat with little Johnny and their parents, plus Sarah and her new husband living in the UK, and Bob on his trip in the Philippines. The reason I think this could be significant is because it's a potential "killer feature" that might drive adoption with "everyone else", i.e. people who aren't techies, aren't hanging out on this site, but love Facebook because it lets them (re)connect with people easily, and love Skype because it lets them see and hear their loved ones for free. Google is giving them more, and it's giving it to them in the context of a social network. People will want to be able to do this, and the only way - so far as I know - is through G+. So sign up to G+ and you can group chat with anyone you want, for free. This could be a big incentive.
Back to the Home page. The "stream" (like FB's wall) is nicely formatted and clean, and otherwise almost exactly like FB's version. All the controls and tools you'd expect are there including who is involved with a given post (for Hangouts it shows thumbnails of the people who were there for example), details of the sharing status (public, with particular groups, etc.), the ability to comment on, +1 and share any post, to mute a post/thread or the entire person or report abuse, etc. You can even disable comments and reshares on individual posts which is quite nice and another privacy-preserving feature (after all, just because you post something privately doesn't mean others will keep it private!). There are also individual streams for each Circle as well as an aggregate stream.
Another piece of the puzzle is that new black Google bar you've been seeing on the Google home page. When you're signed in to G+ it follows you around on any Google web property, letting you easily share, +1, and do other G+ type stuff. It's nice to have and I'd even like the option to let it follow me around on general browsing to make sharing easier from other sites. I imagine they might implement that sooner than later. Surprisingly +1 and other features don't appear to be rolled out across all of the major Google properties even, with YouTube one notable omission. But Shopping, meanwhile, does have +1, as does the general web. Interesting.
Last but not least, there are lots of controls in your G+ settings allowing you to adjust notification types and methods (you can even be notified via SMS). The "Data Liberation" system you may have heard about is built right in to the settings, allowing you to export data for Picasa, your Profile, Stream, Buzz, and Circles and Contacts. Facebook has similar functionality, although it didn't debut with it, and I haven't compared the two. But the easy accessibility and existence of the feature right from the start is very nice. You can also, interestingly enough, link other accounts with your G+/Google account, including Facebook, Twitter, Flickr, Yahoo, and more. I'm not entirely sure what the linking really does yet, but it at least (optionally) adds a link to your page on that service to your profile's About area.
The one thing some have said is odd is that it's not integrated with Gmail like Facebook's new "messaging center" email thingy. I don't think that just because FB is doing it Google should too, but I do note a distinct lack of a real "private message", "direct message", or similar type feature (as far as I can tell). Your G+ contacts are your Gmail contacts though I think (haven't tested whether adding someone through G+ adds them to my Gmail contacts though), so theoretically you can just jump over to gmail to email them if you want. There's also direct chat and Hangouts. Still I see this as something that needs addressing somehow. Many a mini embedded Gmail interface or something.
Last but not least, Google nicely includes a slick Feedback tool/link. Clicking Send Feedback in the lower-right of any G+ page pops up a nifty feedback tool. It has the comment form you'd expect, but also tools to highlight or black out multiple areas of the screen just by clicking and dragging. Highlight and blackout areas can also be easily removed. When you're done marking up the page and commenting, you preview your feedback and it shows how they'll receive it. This is all very nicely done and makes giving feedback easy and even kind of fun.
Now I should mention that my impressions about the UI might need to be taken with a grain of salt depending on your perspective. I hate and have always hated the Facebook UI and find it very unintuitive. I'm usually quite good with web UIs and software UIs in general, so it's always frustrated me that FB's is so opaque to me. Google's is much better, but I don't know how objective that is. I'm curious to hear the opinions of people here as I trust the viewpoints to critical, diverse, and interesting.
I've also just installed the Google+ Android app but haven't had a chance to play with it much yet. The UI is fairly nice though and some good ideas like auto-upload of new photos and videos for later sharing. So I'm looking forward to exploring it and expect to be using it much more than FB's app.
Overall I'm impressed and I was *not* impressed by Wave or Buzz. They appear to have gotten this right for private beta, and hopefully the rough edges will me smoothed out soon so the whole world can check it out. I'm super curious to see if this makes a dent in Facebook's domination. Like I said there are some potential killer features (Circles, Hangouts) that might just make the difference...