Wife has one (which makes us an iOS, Android, Windows Phone family - do I get anything for the set other than a big bill?) and she really likes it.
- Fast, simple UI.
- Actually works as a phone.
- Camera, video, screen are great. Haven't use the music bits, but it's got the usual stuff.
- The 'tiles' integration bits are pretty neat
- Apps. If you are really into apps then at the moment Windows Phone is a 3rd place at best. You get things like Angry Birds and all the usuals, but not the latest/greatest. My wife doesn't care, and hates Apple, so it's not an issue
- It can do all sorts of Xbox Live and microsofty integration (Office etc) which you have to either ignore or turn off.
Having played with it a fair bit, I think it's actually quite nice and a decent smart phone. Android can be fiddly, and iPhones you pay premium, so there might be a '3rd way' for Nokia/Microsoft, especially as they get the price right.