We just got back Wed, we were there from the 11-24. We bought the Virgin Mobile USB modem for the trip. Not the Mifi, just the single one. You know, I'm not overly impressed. I also used it en-route, and at a couple of other places we stopped. It worked, sort of. There were some things I was simply unable to load, at all. There were quite a few times when it took several tries to get a web page to load.
I know it depends on what you're loading and all. Most of the time we were gone I was not able to get my Facebook games to load, but those do have a lot going on in them to load. But Hotmail doesn't have all that much going on, and I had problems a number of times getting it to load.
I think if you really *needed* it to be reliable, like it was for work or something, you might want to explore other options. If you're just using it for pleasure, email, whatever, and it isn't a big deal if you have to fuss with it a bit, then it's a good way to go.