I am on the fence about the same thing. I can take the crowd, but I'm scared to freeze at wdw!!! I know I'm going to get flames for saying I'll freeze in Orlando, but I just hate to be cold, even if it's "cool" to some people.
I did this once and had a great time. The weather is iffy, but when we went it was a little colder than average. You could luck out. The lines are really long the Friday after Thanksgiving, but if you go early with a plan, you should be fine.
Crowded and more expensive than the week after Thanksgiving. Even the restaurants increase their prices for Thanksgiving Day and getting a reservation could be rough if you're planning to go this year.
Decorations for Christmas will be up by then. Osborne Lights will be running but MVMCP will not have any dates during that week.
Weather can be anywhere from hot to mild to freezing cold (for Florida). I have friends who would go every year during that week and they had to buy hats and gloves one year because it was so cold. They have pictures taken in front of the castle with their winter coats on. OTOH, we were there the week following Thanksgiving in 2009 and it rained all day, pretty much every day.
Best kept secret is the week following New Year's Day. Mild, generally dry and if you get there early enough in the week, the holiday decorations are still up. No MVMCP or Candlelight Processional but the crowds are almost non-existent.
We went a few years ago and it was a bit cold at night. NOT freezing but I wish I had packed my little strechy gloves and a hat or ear muffs. There was a breeze when we were watching the fireworks and it made it cold. I did take my spring jacket and was fine with that.
If you have not made dinner reservations it might be tough to get. We did the Ohana Laua for Thanksgiving day. It was so nice that it felt like we were eating among family and friends.
Be prepared because it will be overwhelmingly crowded! Avoid DTD. We arrived on Tues of Thanksgiving week and it was quiet at DTD but Wed was a nightmare. Wall to wall people and you could not shop because the stores were so crowded!