We were there this past January 25th-February 5th. It was delightful. Cool temperatures (70s or so by the afternoon, but we would start the day in shorts and sweatshirts, and by lunchtime, the sweatshirs were in the backpack), minimal crowds. The hours were a bit down, but we did get to see all the parades (including Spectro), and all of the fireworks.
We even swam a few times. Disney keeps their pools heated very nicely, so it is only cool when you are getting out.
We are going to continue to visit at this time of year, until DS is too old to pull out of school.