Went the last week of October 2005. Be aware that this is hurricane season, though.
We had a great time, and the weather was great, but we were impacted by Hurricane Wilma. It arrived two days after we did. The night before the hurricane, we got caught in a torrential downpour. The next day (the day the hurricane hit) we had 50 to 60 mph winds and rain, but it blew through very quickly. The parks didn't open till 2:00 p.m. that day. The good thing was, the first couple of days (pre-hurricane) were quite hot and humid, but after the hurricane went through, the weather was beautiful! Upper 70s and no humidity.
Regarding the crowds, they were quite reasonable. Epcot was the busiest due to the F&W festival, but it didn't impact us very much. I think it's a great time to go!