New member here... we switched to T-Mobile in August 2015. I am mostly happy with the service, and VERY happy with the pricing! Plus, I love the fact that we can use our phones in Canada and Mexico just like in the US (we're on the Simple Choice North America plan), and use text and data around the world at no extra charge.
On the down-side, it seems that T-Mobile's coverage in other countries is far better than in the US. We made a drive from San Diego to Seattle last year (in 2 separate vehicles, helping a family member move), and every time we got outside of a major metropolitan area, especially in northern CA, our signal pretty much disappeared. We were without coverage throughout most of Oregon, aside from when we went through the major cities -- Eugene, Salem, and Portland.
But what bugs me the most is that I have practically NO coverage inside my building at work! I work in the Carmel Mountain Ranch area of San Diego inside a 2-story building. Outside, I get full 4G LTE coverage. Inside, I get 2G (Edge) at best, but most of the time, no data. Even texts often fail to send. I have to use WiFi calling to get reliable phone and text service, which I can do, but I've also noticed that every time I move from one part of the building to another, if my phone roams from one wireless access point to another, it loses the connection, then re-associates, and half of the time, WiFi Calling gets stuck trying to re-enable itself, and I have to turn off WiFi, disable WiFi Calling, turn WiFi back on, wait for it to connect, then re-enable WiFi calling. Sometimes, I have to restart the phone.
I just saw an ad while watching a YouTube video this morning about how great T-Mobile's indoor coverage is. Um... not so much! Other places, too, if I go inside, I often drop down to 4G or Edge.
I just came across something about the different frequencies and bands on LTE. According to documentation I found, my Note 4 supports the various bands T-Mobile uses, but I'm wondering if there's a way to force the phone onto a particular LTE band? I *am* able to force it to GSM-only (2G), which seems to work a little better for voice/text, but of course, data SUCKS at that speed.