Had no idea this existed until I saw this thread and a few other posts. My TMobile SIM arrived last night so I can compare to my current AT&T coverage; activated with the $30 plan online with no issues, except that there were no numbers available in my area code, which was mildly annoying.
Coverage in my area so far is equal to AT&T...at half the price I currently pay. I rarely use 100 minutes most months, so a combination of keeping a little extra in my account for overages and using Google Voice through the Hangouts app for outbound calls when I'm on wifi should work perfectly--especially since I'm on wifi nearly all the time anyway. Now I just need to port my number over from AT&T and pay ETF for the last four months of my contract. I'll still save money even after paying that off.
It works fine....I think that is super old info. The iP5 was the first phone that was officially supported by T-Mobile and only certain ones made after April 2013 had all of the frequencies T-Mobile uses. These statements are more about warning that certain old iPhones don't work. I'm using the plan on an ATT 6+. The VZ model has all the same bands and will work fine. I first signed up for this plan on my iPhone 4 and have simply moved the SIM to a 5, 5S, and 6Plus with no issues at all.
1) I know that my iPhone 5 will work on T-Mobile but my understanding is that I can only get 2g speeds with it? If so, I'll sell it and buy a 5S.
1) You may want to try it on your 5 first...it may work better than you expect. If you are in an area that has implemented LTE, then it's likely that T-mobile has also refarmed other frequencies so that you may get "4G" which is HSPA+ on your VZ iphone. In some areas this is nearly as fast as LTE. If you aren't happy, you could then get a 5S.
I'm using my unlocked AT&T iPhone 5 from January 2013, and I'm getting LTE in some areas--and at speeds faster than my AT&T service provides. (Sadly, not in the house--but I rarely hit LTE speeds in the house with AT&T either. For me, they're pretty comparable in terms of voice and data signal--they equally suck at home, but are still usable.)
So to those worried about speed on an iPhone 5, if your phone is already GSM unlocked, definitely get a SIM and just try it out--even if you go with the per day rate for a few days, you should be able to get a feel for whether or not it will work for you. TMobile pretty frequently has sales on their SIM online; two weeks ago it was free, up until a couple of days ago it was 99¢.
(And their coverage doesn't work well for you, as others have mentioned, Cricket Wireless has a comparable prepaid plan running on AT&T's network.)