The device is pretty small and will easily slip into a pocket or bag, the MiFi also appears to hold a charge for a good while. I've heard quite a few people expressing interest in this as they have bought, or are thinking of buying a WiFi only iPad and indeed this is a very good solution if you're thinking of buying the non-3G version of the iPad.
There's an added bonus in that the MiFi will provide Internet connection for any other WiFi devices that you own too, e.g. I can easily connect my iPhone, or Macbook Pro using the WiFi.
I'll have more details to post later, after I have a chance to test it out more fully, but I can say already that I've seen some surprising speeds from it around my home town of Lisburn.
So far, so fast then, more later.