S. Elop in an interview recently said the Lumia 710's exceeding expectations in the US market.
The 3.7" display, 5MP Camera, 1.4GHz processor WinPho7 phone went on sale with T-Mobile (now $39/2yr on contract) in the second week of January and has gotten on greater than expected reception from T-Mobile Users (old and new). It runs on T-Mobile with 4G speeds
It had a huge marketing blitz, I cannot count how many times I have seen Lumia 710 commercials either on the internet, on TV or even in my Junk mail!
The Lumia 710 is currently in the top 3 phones being sold by T-Mobile, in front of T-Mobile's own "MyTouch" android phone, , it means US consumers are welcoming the Lumia 710 with open arms, which is good news for both Nokia and Microsoft; as they have struggled to make an impact in the US market.
Let's now wait and see how the Lumia 900 does when it is released in "God knows when"