We were there in 2012. Oct 21-26. I thought the crowds were just fine. Most waits for rides were an average of 10 minutes. Some were walk on and some we waited 20 minutes. I think the longest we waited was 35 minutes for Dumbo.
BUT, I will say that we followed Josh's advice of recommended parks every day and that meant we only went to the MK on days it hosted the Halloween party. We also went to Epcot on a Monday and to Hollywood studios on a day it closed at 6. We were also at the parks at RD too, and had an itinerary for the first few hours. So we didn't just luck into low waits. It took some planning and strategy.
However, I do have to say the trip was wonderful. We went with extended family and they all commented how nice it was to not wait in long lines.