I spent nearly a few days in my spare time going through this thread. I have an iPhone 5 that is locked to AT&T. I am one year into my contract and the ETF is $175 at this point. Since I'll be saving $60/mo. the payback period for the ETF expenditure is roughly 3 months.
I noticed some people claim that building penetration is an issue at times. It can't be any worse than AT&T. There are times I go to a friend's house in the middle of Brooklyn NY and the signal is so weak I can't even surf the web! If I go to a restaurant and go far from the window, the service sucks. It can't be that much worse with T/Mobile.
Oh yes it can....
Did a trial run with T-Mobil the other day, going from Verizon where I got great coverage, and about 30/35 Mb download speed, and around 3 to 7 Mb upload. LTE coverage where ever I drove to as well. No 3G except in one restaurant.
T-Mobil rep, after signing up at the Mall said, even though I was now getting 2 bars and 3G inside the Mall, once outside I should get 4G or LTE without an issue. So I tried out T-Mobil, walked outside the Mall door, and got no LTE, no 4G, no 3G and not even "Edge". Walked a block to my parked car, and got "Edge" coverage. Interesting.
Got home, and went inside, and notice I would only get Edge coverage. My home is built with concrete, and steel. Went across the street, and got 3G briefly in the parking lot, than down to Edge within seconds. Went inside the restaurant, and got no coverage or Edge. Back and forth for some unknown reason.
Tried Speedtest outside of the Mall, and would not connect. Inside the restaurant SpeedTest did not work. At home it did not work at first, but once it did, it showed
around 1Mb download speed, and a few Kb's upload. It went down hill from there, and I got less than 30 kb download speed at the same location. This fluctuated up and down within seconds doing the speed test.
Voice sound quality was not good either. Talking with a T-Mobile rep, the voice was crackling where I had to ask the rep to repeat. Called my brother cross country and he said that I sounded as if I were inside a tin can or such. Not good.
So, it really depends on where you live if you get good coverage or not, and what type of building construction as well. The T-Mobil coverage map indicated I should have gotten 4G inside my home and outside as well. This did not happen, so I canceled T-Mobil within hours and returned to Verizon. T-Mobil for my area will improve, but not today.
Location: Dunedin, Florida. 18 miles from Tampa Florida