I am very happy to read this. I have been a T-Mobile customer (from the early days of VoiceStream) and they have never given me any problems.
In fact, they let me replace an eBay bought phone with a new Tmobile one just because I had the handset protection plan (from years ago).
This is a company that provides comparably good service to both Sprint and Att and charges 3/4 of the price.
For $50 a month I am getting the unlimited 3G/Talk/Text with them, which is unheard of for ATT. Happy with my Windows Phone 7 and Tmobile :)