I have slept on them on occasion at hotels, and I hate them. I can never get a setting right, and if its a king, there are 2 separate sections, but I would always wake up right in the middle of the bed on top of a metal bar. I will never book myself at a hotel with these beds.
We keep seeing the commercials for them, we're sort of torn on whether we'd want to get a Sleep Number or a Tempurpedic if we had the money for a new bed.
Considering our current mattress stabs us with poking out springs every night, either one would be a massive improvement.