In one word: Don't.
In more: WP8's pros are not worth the jump. And there are significant cons too.
WP8 is not bad, and gets better by the time. For instance the new 8.1 update will bring a proper notification center. Previously you had to use live tiles (the rectangles, large and small squares on the home screen) to provide notifications. But they provided only limited notifications, and even then they were not accurate. For instance samsung's chat-on client did not reliably show the messages in the tiles until you opened up the app itself. It may be an error on part of the app, but I saw the same problem with numerous apps. Android's notification system looks much more issue-free in comparison.
WP8 is not that customizable. Sure, it's customizable in comparison to apple's banknote press, but in comparison to android, it fails bad. Just an example: you can't switch to another keyboard like swype. WP8 keyboard is not bad. Just what you expect out of a stock keyboard, but you may be looking for something more, and there is no option to get it. So switching to WP8 effectively limits your options.
The APIs WP8 offers are thoroughly locked down. You don't get a proper file manager, because many sections of the file system are off limits to third party apps. There are rudimentary file managers, but they are not of much use. In a similar vein, you can't record (as audio files) the calls you make. Android apps like
callx are not possible in WP8. If you need that function (mom does not, but I do; speaking to tens of clients each day, I can't always take notes of what they order, so I record the calls) WP8 is not an option. You can't add apps like
blacklist because there are no APIs for those functions. These are just a few examples. WP8 is much more locked down compared to android, that you can't do much with it.
If you like tinkering with your phone, have rooted or consider rooting the thingie, WP8 is not an option. No rooting whatsoever. End of story. But as I said, the customization options are limited even compared to non-rooted android.
Appstore is growing, but still is way, way behind android. Just out of my mind, there is no booking.com app for windows phone. And no,
this isn't for windows phone. You have to do with the also-ran hotelz.com. And because the APIs are thoroughly locked down, the app store will never be as rich as that of android.
The settings are crowded and disorganized (or at least organized in a way incomprehensible to me). Some functions such as call forwarding are located in weird places.
Battery life is nothing to brag about. Nokia, I don't know why, uses very conservative batteries. For instance, my LG L4 II has a bigger battery compared to wifey's lumia 820, despite mine being a single core and small screen phone. I get 3-4 days use out of a full charge, wifey often does not get 1. There are exceptions to this rule, I hear. For instance lumia 720 is better in the battery life scale, but I don't hear praises about 1520 either.
WP8 does not really multitask. When you switch apps, the old app is not just pushed to the background. It is suspended in effect. There are exceptions to this, for instance the music player and voice guided navigation seems to work in the background, but as a general rule, the app you push to background stops. When you return to it, it just resumes from where you left. So you can't have apps like
noom, because once in the background, they will not be able to continue counting your steps. sucks. really. hard.
On the bright side, the OS is more responsive, especially compared to landfill android. Yeah, I get better battery life, but my phone often makes me wait for a couple of seconds, especially when I am in a hurry. WP8 feels way faster in comparison. Not just high-end devices like 820, but lower end ones like 620 too.
Nokia's here maps and navigation suite is way way way better than what android offers, assuming you don't have (or don't like to use) data connection. Google maps and yandex maps are not bad, but they need constant data connection (which is not an option when you are roaming, or low on battery). Nokia's maps are offline and very good. You just download the map for the country you live in (or you will be visiting), and you're good to go. I know there are offline maps you can download on google play, but they all suck. really. hard. Openstreetmap based solutions are not an option if you need a reliable map. And they are not an option if you are in or will be visiting developing countries like Turkey, period. The maps is the single most important advantage Nokia's phones offer over android, and they may be important enough for you to justify the jump to WP8.
Finally, the updates: Microsoft seems to offer updates to the whole WP8 line, regardless of how old or how underpowered your phone may be. The platform as a whole gets new updates. So every WP8 phone will move to 8.1 in the near future. But your guess is as good as mine about what will happen when WP9 comes out.
edit: typo fix.
edit^2: Nokia released its
maps software for Android. So you have one less plus for WP. Thanks goes to 4wd for alerting me to it.
