To date Verizon Wireless has for the most part been on top when it comes to bandwidth and reliability. Now with the combined networks of the existing AT&T (formarly Cingular [or SBC and Bellsouth Celluar]) and TMobile, AT&T may actually have the upper hand.
Now all of this is of course pending approval of both the SEC and the FCC so there is going to be some talk about this in all of the media channels used by politicians. My take is that it's a smart move. It's not too big to be blocked this time but another merger of this size would be more difficult and protracted. In other words a merger of the two CDMA networks in the US will have more scrutiny than this one will.
That said, I'm not so sure Verizon Wireless is really interested in going after Sprint. They just acquired Alltell Wireless in 2009 and they are busy deploying their new nationwide 4G network based on the latest TDMA technology called LTE. It is being deployed using the new 700 MHz spectrum license bought at auction from the FCC. The folks at Verizon Wireless have enough on their plate right now and the new spectrum will compete nicely with combined AT&T/TMobile network.
My guess is that it will go through. It will take some time, like until 2013 or later but it will go through. Overall this is a much better deal than a TMobile/Sprint deal if simply for the compatibility of the networks. Not to sound to ominous I think we are headed towards a duopoly of national cellular carriers. The winners are AT&T and Verizon Wireless. Vzw will buy Sprint or Sprint will go under. That might take another five years or more but ultimately we'll end up those two carriers so get used to it.
There's my two cents.