I had a FreedomPop hotspot a few years ago. I used it when I was overnight pet sitting for clients with no wifi, or if I ran into connection problems. You could get 500 mb a month free then. But the coverage area was limited, so sometimes I still had no connection, and then they discontinued my hotspot, telling me I had to buy another one. Fortunately, by then I didn't need it anymore.

Aside from those problems, it served my purposes pretty well.