We have slept on them before. I thought they were fine (not bad, but not as nice as our sleeper sofa at home) but my wife did not like it. She would sleep on them again in a pinch but would prefer not to. This is why we try to get the kids to sleep on it instead of us.
We had one at BWV that was fine to sleep on...of course after being in the parks all day we were very tired. But it was a beast to open and close! Really tough. Group decision not to have them working on it during our stay (the men apparently didn't mind the struggle as much as I did for just a few nights) so we mentioned it to maintenance on check out.