Just switched to a Nokia 822 running Windows Phone 8.
Great UI & touch response. Absolutely love the live tiles, it really does save time by allowing me to see certain things update on the fly so that I don’t have to dig deeper opening those apps. Less function & detail control than Android (I think they tried to balance between the Apple iOS’ simplicity and Android’s level of customization). Great specs for processor and battery, excellent screen resolution and clarity. Fit and finish is what I expected from Nokia (very good). My Droid phones had terrible fit and finish in comparison.
My few frustrations include the immaturity of Windows Phone OS and their marketplace. A few apps that I had on Android aren’t yet on WP and some that are require complicated transition of data (luckily, only 4 or 5 apps out of 30 or so that I use are giving me that transition grief).
I chose a Nokia over an HTC or Samsung Windows Phone because of the turn-by-turn directions (Nokia provides their GPS database to the likes of Yahoo & others and it is free on their Windows Phones). It rivals the excellent turn-by-turn experience Google’s Android phones offer.