This video compare Lock Screen, UI Design, Multitasking, App Stores, Music Player, and Browser pf Windows Phone and iPhone.
Watching this video will expose you to a lot of features in Windows Phone. For example, I never knew about the Fast task switching option in Windows Phone Mango.
I guess Apple is still the best choice than windows phone. Windows phone should prove that they are worth the money first and a lot of people are using iPhone now, so I'd still go for the Apple phone.