This review ( especially its negative tone) partly applies to anyone looking to use this phone with TMobile as your carrier, since that's my experience. But for all I know, the phone may be similarly stubborn about working with other U.S. carriers given that it's a Euro-centric device made by a Euro-centric company.
Therefore, I have to recommend that American customers stay away from this phone: despite its nifty feature set, there's just too much risk of things going wrong, and unless you're a mobile techie, it's a major headache trying to fix the bugs ( assuming they even can be fixed).
First and foremost, TMob doesn't have proper configuration settings for this phone; instead, they sent me settings for a similar phone, and when problems started to crop up, they told me those were the only settings available.