"Continues Nokia's tradition of quality and style"4.5 starson by ds_k7
Pros: Beautifully designed, smooth navigation, high quality speaker, simple interface, great camera & video, amazing message & social media interface.
Cons: Minor inconvenience in lack of customization options for phone ringing settings (i.e. no way to set sound profiles such as 'Normal', 'Silent', 'Office', 'Meeting', etc, but i'm not even sure if iOS or Android can do this either).
Summary: This is the first smartphone that I have owned, and I specifically held out for THIS one after owning a Nokia 6010 for 7 years. Yes, seven straight years with one type of phone. No other smartphone appealed to me despite all the hype about iOS and Android.
Lumia 900 carries with it Nokia's reputation of high quality builds. Windows 7.5 Mango is simple, straight-forward and artistic. Though a few additional customization options would be nice (such as being able to individually control the ringer volume and the text-to-speech volume), this is in no way a deal breaker.
Synchronization of contacts between Facebook, Windows Live!, and Google was straight-forward as well, though I only have myself to blame for the clutter (some contacts from Windows Live are over a decade old). Facebook app is easy, though mostly obsolete thanks to the 'People' tile.
The screen itself is goreous and on par with the Galaxy S II's AMOLED+ in terms of color, brightness, and viewing angle. Speaker is loud and clear, call quality is good. The phone features voice recognition for speech-to-text and a few phone commands (such as "text this person" or "listen to music") which I like.
Syncing with Zune was easy, but I had some problems with DRM on old CD's which I had ripped years ago. The Zune software itself lacked a few features (i.e. you can't choose which options you'd like to sort your lists by; instead its only "Albums", "Artists", "Title", etc) but again, not a deal-breaker.
As of this point, I really haven't found anything other phones can do that this one can't. I haven't spent much time around the app market, but as of this point, I've gotten everything I need and want (such as Music Alarm Clock and Adobe Reader). The phone is great for business and work-related items especially (having a condensed version of MS Office which includes Word and Excel as well as a PowerPoint viewer) and as a student, I can read and write assignments on the fly. I would really like to see MATLAB for mobile platforms, but I think that's just impractical for any phone, unfortunately.
Despite the fact that it's a Nokia, however, I would still recommend buying a rubberized case for it and a screen cover. Fingerprints show up easily and the case is a little slippery if you don't have a full-handed grip on it. With a case, the thing could probably stand up against a nuclear bomb. Without one, it might only hold against an atom bomb ;)