We were there for the week leading up to Thanksgiving in 2013. I think the weather was perfect--but we're from Ohio, so 60 degrees generally feels warm to us around that time of year.
It was chilly enough in evenings and early mornings to need a jacket or sweatshirt, but it was never freezing. We would wear lightweight pullovers to the parks and then remove them by around 10:30 or 11. The afternoons were beautiful--usually between 60 and 70 degrees. We tried swimming a couple of times, but I'm not totally convinced that the pool at POP was heating properly. It wasn't a pleasant experience.
Florida is unpredictable, though! I ran during the WDW marathon weekend in January of 2013, and we were running in 82 degrees!!! It was crazy for that time of year. Bring plenty of clothes you can layer, and plan for any and every weather condition!
We'll be there at the same time again this year, and we're hoping for similar weather... though a couple of higher-temp poolworthy days would be ideal!

I really think this is the ideal time of year to go, though. Crowds aren't bad at all until maybe the day of or day before Thanksgiving, the weather is beautiful, all the Christmas decorations and celebrations are in full swing, there are very few closures because they are anticipating larger crowds for the holiday season... It's wonderful!