Yep, I actually have a $20/mo (2GB/mo) data-only T-Mobile SIM that I've used extensively for international travel the past year that's worked great (anything longer than a couple days I'll tend to pick up a local SIM for my primary phone, but I leave it in a secondary phone and have never had any issues either way. Speed is perfectly cromulent for messaging and navigation.)
Is it actually worldwide though?
Their site says
> PLUS use your monthly 4G LTE data in Mexico and Canada like in the U.S., at no extra charge
Internationally you get $0.20/min calls and unlimited 2G data. I'm getting a consistent 0.07 Mbps in Buenos Aires the last few days!
> PLUS use your monthly 4G LTE data in Mexico and Canada like in the U.S., at no extra charge