I am on a grandfathered unlimited plan, so I am not paying very much due to the multiple-line discount. They are a bit all over the place in their offerings (Reddit has the horror stories), but the service has been fine, even in my my very large urban environment.

It's a mixed household here, T-Mobile and Verizon, which was the original attraction to USM. I kind of see it as the MVNO equivalent of AS Mileage Plan (in the old days), which has some value.