Yes, Tmo is catching up with ATT and VZ on quality, the main reason they bought Sprint (remember them) is because Sprint had a shit ton of spectrum but they weren't building it out because they were capital starved (for a bunch of reasons). So now, TMo has the most low and medium band spectrum and they are catching up on build out. Vz has the most spectrum if you include the mm-wave, but it's difficult to build out.

All the bandwidth competition is a good thing for the consumer and hopefully some cool stuff gets developed to take advantage of it.