Last December we were at Movies and never waited long for a bus at all. Even though this is one of the slower times at Disney, there sure seemed to be lots of people at the resort. We waited no more than 10-15 minutes for the bus, and that was after just missing the one before. On one night the line was extremely long waiting for the bus back from Epcot. The first bus came and it was obvious everyone was not going to fit. Before the first one even left an second bus was waiting behind it.
I have read reports af people getting spotty bus service at all the resorts, even the most expensive ones, but i personally never had a problem with ASMo or ASSp. I have been nothing but pleased.