I'm wondering also. So far I have been running the official Hotspot app for almost a day and a half, on and off. It seems to disconnect a lot even in a heavy 4G signal areas. I have also connected it through the USB cord and it works perfect without disconnecting. It seems there are some bugs with the true mobile hotspot app.
I have burned through 2GB of data already but it all shows up under my "unlimited" phone data section in the Verizon website. The only other data section I see is the Mobile Broadband data bar and that says I have used zero. I do have 4G services so its eating through the data like crazy. I was streaming the NCAA games today also. It works great.