Personally, I'm glad of this, although on one hand it goes against my general "keep your mitts off of business" you government regulators. On the other hand...
I suffered through what I considered extremely poor customer service (and seemingly poorly trained/knowledgeable support personnel) with AT&T for several years until I finally changed carriers to T-Mobile.
I would hate to be forced to "go back" to AT&T, nor do I blindly trust them to make good on their unenforceable promises.
The T-Mobile customer service experience AND connection reliability where I live has been far superior to my experiences with AT&T in every way.
Of course I realize this may cause a big problem for T-Mobile in the long run (see article)...or it may make them stronger if they can find the right leadership and/or financial partners. Nor do I care for Sprint by the way.
However, it's also possible AT&T has improved its customer service and reliability since I last subscribed to its services. If the merger goes through I certainly hope that is the case.