I've had Millenicom.com for about a year now. Used it at home for my home computer usage and now use it for full timing. The MiFi is sitting in a Wilson Sleek right now.
The hotspot functions as a router and will run about 6 hours or so on a charge. Can put it in your pocket and sit in a park, or at the beach - run a tablet, notebook PC, Nook, etc. I usually just leave mine plugged in all the time. You can run up to 10 devices on it if I remember correctly. I also have my Iphone set to use it for data purposes if in range.
Runs on the Verizon system, which was a main point for me. $69.99/month. Seems like a deal. And as others have stated you get to talk to real people up there in Portland if you need customer support. What's not to like ?
Tim