I have 3 times during the year that I prefer to vacation in Disney World: beginning of February and May and December.
My experience with February has been a good one overall:
1. Weather: Like the other posters noted, the weather can indeed be all over the place, but being "too hot" is definitely not a concern. I remember on my last February trip (Feb. 1-6, 2009), my DH and I had to buy an extra sweatshirt, hat and gloves (thank goodness I packed all my DD's winter items in our carry-on). Looking back at the pictures, it's kind of funny to see my DH and DD all bundled up in their winter gear just to ride Dumbo! (The high that day was 45 and the low 35; definitely a cold snap

) And, I do recall not having a single day where the weather was mild enough to go swimming. However, that didn't stop some resort guests; the pools may be heated, but that frigid air was enough to keep us away.
2. Crowds: Moderate to low during the first 2 weeks. We were able to tour Fantasyland on a non-extra magic hour day, arriving an hour after opening, in less than 40 minutes. We didn't have the park to ourselves, but we sure weren't competing with crowds for even the most popular attractions.
3. Refurbs: Sure you might run into some, but you can look forward to touring the Fantasyland expansion to make up for other closures!
Noting that you're from Canada, pack your winter coat (not the Gortex (sp.?) kind), hat & gloves in your carry-on, a swimsuit (just in case there's a fluke heat wave), and the camera to capture memories made in the expanded Fantasyland!!:wave: