I must say that I am more impressed with T-Mobile Customer Service everytime that I deal with them. I have read some criticisms on T-Mobile on other forums but can't say that I have ever had a bad experience with them.
Just tonight at 2:45am in the morning I called them to see about changing the phone number on my new Dash. I explained that a random number was assigned to me and I wanted a different area code. The young lady I talked to was extremely pleasant and changed the number and waived the $15 processing fee for me. Seems she just got her Dash today as well. She even apologized for me not having been able to specify which area code I wanted when I ordered the phone.
I never had consistent good customer service from Cingular or Sprint like I have had with T-Mobile. I once was on hold with Sprint for over an hour and a half. Cingular was okay but it seems like the folks at T-Mobile must be required to take a course in being pleasant over the phone.