We LOVE WDW at this time of year.
It's got the potential to be 'cool', but since we are from New England, we would start the day in shorts and sweatshirts, and end up in tshirts by mid-day. Sweatshirts or jackets for the evening.
There are little to no crowds, and the only downside to that is that the parks do close earlier. But because there are very light crowds, you can get A LOT done.
We've done 2 end of Jan/beg of February trips, and simply LOVED them. Now, we try to tack on a few days before President's Week, so DS is not missing a ton of school.
Any other specific questions, fire away!!