AT&T does suffer from congestion in some markets and they are slow with VoLTE and Wi-Fi calling.
Overall though their coverage is pretty awesome.
I have given AT&T a lot of flack for being slow to rollout new services and for their LTE speeds dropping. However I have noticed speeds on the increase in my area of SoCal so for me that's promising.
I've seen the good, the bad and the ugly with AT&T and other carriers. They all go through phases where one day they are awesome then the next they are sub par awaiting the next round of upgrades.
I will give AT&T credit for somehow getting at the very least HSPA coverage even in the middle of nowhere. I think they have more issues in crowded markets. They need to step up their CA efforts, REV 10 upgrade and then they should post some nice improvements in overall speeds.
