The problem is not the Adsense ads themselves on sites, but how some people display them. They are relying on a single type of ad, placing it in a rather obnoxious way, and it can be quite annoying. If used properly, Adsense works on the right type of sites, without having to resort to being obnoxious with them. It's the people that abuse the ads that are ruining it for everyone.
I have been playing around with various ads on my blogs and I have found there is 2 types of ads and 2 types of visitors, so figure out what kind of traffic you have and use the right ads.
1. Hit & run info seekers. They come mostly from search engines, mostly from Google, and they respond well to Google's own text based contextual ads. You only need a simple strip with a few ads in it across the top and bottom of each page they see...not a huge block that makes people have to scroll to get to the content.
2. Loyal repeat visitors that usually end up blind to Google's ads on your site and respond better to something like Project Wonderful's
125 square ads and the smaller buttons, which a great many blogs and web comics use to advertise on each other's sites. This ad program is mega cool because of the interesting advertisers.
And if you publish a webcomic, it is better than adsense, because Adsense can't contextually match an ad to your comic images (there is not enough text), and usually gives crappy ads nobody will click.
I use both on my blogs and sites, but I use Project Wonderful a bit more. Rather than it being pay-per-click, it's pay-per-day and you will get paid whatever someone has bid on your ad box, regardless of whether anyone clicks the ads or not. (and yes, you are allowed to click the ads on your own site, unlike Adsense) You also get a lot more control over who is advertising on your site. The program has a lot of advantages for both advertisers and publishers.
I wrote a blog post
a few months ago about my experiences with Project Wonderful. Things have changed a bit since then, and I am now making more off of their ads than Adsense, on some sites. (like I said in the beginning, what type of traffic you have makes a big difference) The article will give you a good idea of what kinds of sites are using the service and what you can expect to show up in your ad boxes. (the sites mentioned all advertised on my programming ebooks site) There is also both Adsense and Project Wonderful ads on my blog, and you can compare them and see, as a visitor, which are more appealing to you if you are not seeking info, and if you were.
There is also a wordpress plugin
that will allow you to control who sees ads and which ads they see, which means you can show Adsense to people coming to your site from Google searches, and something else to everyone else.
You can also use it keep your site ad free for people coming from Digg, StumbleUpon, and EntreCard, since those people never click and showing them ads will just damage your CTR and get you budget priced by some ad networks, and in some cases get you accused of "artificially inflating page impressions" and your account revoked.