Switched from VZW about 2 weeks ago and so far, so good. I've been very pleased so far actually. The only reason I had not switched yet (been w/ VZW for about 15 years) was poor coverage in rural SE TN where my family lives. However, the Tmo coverage map recently began showing 4G coverage being fairly extensive in my hometown now. So, I decided to give it a go.
I got to test the 4G service there when I visited over T-giving. Everyone warned me, the Tmo map lies, don't believe it, etc, etc, etc. To my surprise, Tmo blew it out of the water and that map of the area was dang near perfect. I kept my VZW line active during the trip too because I didn't want to lose my current contract until I knew how Tmo would work out. While that was the reason, it gave me a great opportunity to test the coverages against one another. I spent a good bit of time at a hospital in the town next door and Tmo had 4G compared to VZW w/ 3G. At my parent's home both had 4G though a speedtest showed Tmo w/ a 4 to 1 speed advantage. So, I definitely felt better about cutting off the VZW siphon from my wallet.