I'm a new subscriber as of yesterday, and thought I'd point out some big inaccuracies with the official coverage map. I'm a little worried by how off it was, as I consulted it first before signing up for service. I have a T-Mobile branded Galaxy S7, and was visiting family today a couple of hours away in southeastern CT so I was doing a lot of driving and trying to stream music. Service in the north end of East Lyme, from Upper Pattagansett Road all the way up to CT route 11 was in and out of service (mostly out). The entirety of CT route 11 from Salem to the Colchester line was a no service zone, as was much of CT route 2 between Colchester and Marlborough.
These areas all show as being covered on your map, but mostly provided no bars, no service, or "emergency calls only" on my phone. A reboot and a reseat of the SIM card did not help. The phone works fine in my town with solid service verified on band 12, so I don't think it's my hardware.
I've gotta be honest, I'm pretty upset that I spent over $500 on a phone and signed up with a new carrier that may have essentially lied about where I would have service.