Are you sure you have 4G?
Tru at 15c/MB [17c/MB with tax] costs $30 & includes $15 credit.
Uses T-Mobile at 3G [see below] and AT&T at edge speeds.
T-Mobile is 'refarming' its bands to allow 3G in many parts of the USA.
The below will tell you the good or bad news about where you want to use it.
Sightings of T-Mobile 3G/4G/HSPA+ coverage on 1900MHz (PCS/UMTS band II)
Having it available will probably result in more usage--probably a good thing.
Whatever you get, we would be interested in your results and impressions.