I don't know anything about the Nexus, but T-Mobile's service has been great for me on the East Coast. I switched from Verizon about a year ago and with prepaid service spend well under half what I used to. I can also make calls from inside the house again, something I couldn't do with Verizon (except if I stood on one leg in a corner).

It also saves time because it's one less monthly financial transaction to monitor--I just buy a bunch of minutes every few months or so. I recommend it for anybody looking to reduce costs and complexity (start-uppers, for example).