I had the opportunity to use the Verizon MiFi for a few days and it was great. I expected it to work but it goes beyond just working.
Where? It was tested out in the middle of nowhere - well, at a location in South Carolina about two hours from Charlotte. At this spot I had a no AT&T bars, but did just barely have service. I could send a text message but not confident that I would have had much success with a non-dropping call. My iPhone reported the big "E" - that painfully slow Edge network connection. Between the Edge and almost no service signal, even opening an email via AT&T was horribly slow to the point of "why bother". I don't have a Verizon phone (the service that the MiFi uses) so can't comment on coverage bars, but it must have been decent coverage and 3G service (see below).
Usability - setup. When I showed up someone had already configured the MiFi. The configuration involves a one-time process of connecting the device to a computer via USB and going through an easy setup wizard. The person who set it up is a non-techie and had no problems with it.
Usability - get online. I got situated and powered up my tablet. The network was detected right away and, after entering the security password, I was online. It was no different from using a standard wireless router to connect to the Internet. If I didn't already know the connection was via MiFi, I wouldn't have thought twice about it. Later in the day we had three different laptops connected to the single MiFi and none had problems.
Performance. Once online I did a little bit of web surfing and the experience was fine. Honestly, even though the connection was slower that what I'm used to on a daily basis, the experience of web browsing was totally fine. There was no point I had to sit and wait for a page to load. I ran a speed test to see what actual throughput we were getting and it tested at 1.3 Mbps download and 500 Kbps upload. No too shabby. Especially for a location that doesn't have cable or DSL as an option - and one where AT&T service barely registers.
Physical. The device is small and light - surprisingly so. It also has a rechargeable battery so after charged, you can pick it up and move around while online. I could easily stick it in my shirt pocket and walk around with my tablet while surfing the web if I wanted to.
Battery performance. I'm not sure exactly how long the battery lasts but we did use it for a few hours with no problems. The performance was identical whether plugged in to power or not. I did notice at one point that the connection started getting spotty. This was after hours of use unplugged and shortly later it started flashing red (battery dying) so I believe that performance degradation was just related to us running on battery too long.
All in all, it is a great little device and I highly recommend it for people who are mobile a lot and need decent-speed Internet - especially if you need an Internet connection for more than one device.