We went the first week in October last year.
I didn't think it would be as crowded as it was, but it still wasn't bad. The longest we waited for anything was about an hour and a half for Toy Story Mania, but that was because the ride broke down for a little while. We fastpassed everything else. We were able to do everything we wanted to, and then had a couple days left over

We didn't have any ADRs and had some trouble making reservations a couple of the days, we ended up eating at the Swan/Dolphin which have fabulous food anyway, but I hear it's like that all the time now. My dad's funny. We met up one morning and he says, "I tried making reservations for that steak place in Canada you said was good, but they were all booked up for the rest of the week ... and the next few months."
It was definitely less crowded then when we've gone spring break and February break when I was in school, but more crowded than in January or November.
The weather, well, it rained every day we were there, but it only bothered us for about two hours one day. It was a little too hot for me, but I really hate being hot. I much prefer the January weather.