Switched from ATT before the uncarrier stuff and hitting my 5 gig "unlimited" data 2 months in a row. Anyone who switches, either sign up for their test drive or if you have an unlocked GSM phone, sign up for a 2 weeks and pay the prorated price. You need to check if you have coverage of all the places you visit often - home, work, inlaws, parents, cousins, family, dog park .. etc.
Bay Area here . pockets of the East Bay with no coverage, to me not a big deal, either im driving through or only there for a day or so. Bay Area to Tahoe (fine until you're north of Sac). Bay Area to LA (little to none). Bay Area down 101 (little to none) unless you're hitting the bigger cities.
Indoor coverage is terrible, hopefully your market has 700mhz or at least has the spectrum. By year's end, they're supposed to have all edge to LTE, that should help.
Grandfathered unlimited data and they sent me a free wifi calling router. I like them. Just hoping they rollout an update for Nexus 6 to enable wifi calling and VOLTE.