Anecdotally, there are lots of very happy T-Mobile customers (I'm one of them in Minneapolis). I love their prices, service, and what they allow me to do with my phone (in comparison with other carriers). I was also very unhappy with the potential merger with AT&T and have a long, negative past with them that included me filing complaints with the MN Attorney General and the Better Business Bureau. I've sworn never to go back to them again, and if T-Mobile is consumed by them, I'll have to go to Sprint or Verizon, both of which are much more expensive than T-Mobile is now.

If the acquisition moves forward, it definitely has a significant impact on the level of competition in the mobile market.