I used windows phone for more than 3 years. Lumia 630, 730 and 550. To be honest it is way better than android and iphone in terms of usability. I concur with OP that metro UI and all dark theme was the best and unique. I recently switched to android because of lack of updates in the basic apps that I was using. It is still my backup phone. Ohh forgot about the keyboard and unified messaging system. Loved cortana. One thing is I want to point out that all email clients and calendar app should learn to do things right way outlook apps in windows phone did. If you don't believe me use the native outlook and calendar apps you will start hating the google clients. Great jobs phone team at Microsoft!