I have this phone since Dec as secondary phone and about to make it my primary soon. I'm android addict and apple hater but like this phone with all the shortcomings. I just don't like the $200 price. Mine was $160 and looked like untouched display model.
That said windows phone 7.8 is ideal for first smart phone or iPhone/android users that really don't play games/apps etc. I'm surprised how most non geeks don't know how to use navigation/business/advanced apps. Stupid games....not for a $100+ monthly bill. Get this phone or nexus 4 or used android and go prepay you can survive without crap game apps on phone. Get a tablet for that with the $ saved.
Battery life sucks on this just like iPhone 4/most android phones 2yrs ago but I guess people can deal with it. Hell it certainly is better than HTC thunderbolt.
I had AT&T unlock and used it on T-Mobile Data only sim. 5-7mbps in NYC area and tether worked. YMMV.
Too early to know for sure but it seems like my GPS lock went from fastest I've ever had on any device to crap after 7.8 update. No data turn by turn GPS is darn good but still worse than latest Google navigation with data.