I have both a Verizon Jetpack on an unlimited plan. And a AT&T Sierra hotspot on my cell phone shared data plan (3 phones + 1 hotspot share 15gb).
My biggest issue with the hotspots are there wifi network range. Much more than 10' or so and speeds slow down. Throw in a wall and we have trouble streaming TV in our bedroom with the jetpack living in the kitchen. (Even though it LOOKS like you have bars and a decent connection- it still dogs out speed-wise.)
I fixed that by getting a WifiRanger. Much stronger wifi network and it's always on. It gets its Internet typically from my hotspot unless I don't have cellular service and the campground offers WiFi.