According to this review, they got 20 hours using the iPad Mini as a hotspot.

http://www.slashgear.com/ipad-mini-4...izon-03259224/

I think when LTE networks are better settled, especially in Europe, I'll look to replace my Mifi with this, assuming they have a "global" LTE radio on these some day.

Of course, you can blow through data much faster on LTE.