I went to Disney a few weeks ago and we got those as "beta testers," because if you stay at a Disney resort you'll get to use it until they officially and publicly release it for all guests. I loved them. You can hold more than one FastPass at the same time, unlike with the regular tickets where you can only hold one until it expires/is used. We did have some problems, though: two bands stopped opening the door to our hotel room and so we had to take them to the front desk, where they gave us grey ones. It had to do with the technology inside the band or something.
Other than the technical difficulties we experienced, those bands are amazing. Especially for kids.