I made the decision to leave my iPhone behind after using different versions of it over the past 5 years. There wasn't an overwhelming reason to switch other than the cost. I was generally happy with my iPhone, but now that the competition has caught up, it no longer made sense to pay the premium.
In its place, I have a Nokia Lumia 920. So far, I'm very happy with it. It boasts the best smartphone camera ever produced, so I look forward to uploading some new photos using it. It syncs nicely with all my different Windows products so no more transferring with a cable!
I recommend everyone go out to their nearest AT&T store and take 15 minutes to play with it. It might not be for you, but I actually think it's easier to navigate than iOS. That's a pretty bold statement, but I really think Microsoft did a good job this time around.
Also, I bought it on launch day in Times Square. Everything is just more fun when you do it in Times Square!