I had a completely different experience.
First of all, we paid $37.50 for a Buick Century. It was huge and pretty nice.
We were also second seating, got off the ship right after breakfast, checked in with US Airways, got lost on the way to the parking lot (don't ask!), and we just missed one as we got to the spot. We then waited maybe at most 5-10 minutes for the next shuttle. You do have to be a little pushy as people do not really line up and so it's a bit of anarchy getting on. Upon arrival, there were 2 people working the desk and they were pretty fast. It helps a lot if you sign up for Avis Preferred (it's free). Then you bypass doing the paperwork since your info is all on file. We were at Downtown Disney by 11:15 am if that gives you any sense of how quickly the process went.
You should also know that Hertz and Budget were both running shuttles too. I had been lead to believe that their shuttles ran less frequently than the Avis shuttle, but in the time I was waiting I saw 2 of each of those, too, and they were less crowded.