You haven't said what part of February you're planning on going, and it does make a difference. The earlier in the month you go, the colder it will be. I have only been at the end of February and the weather was perfect. Upper 70's during the day and sunny, sunny, sunny. In the evening you might need jeans and a light jacket. Earlier in the month it can be much colder. Crowds: When I've been at the end of February the crowds were extremely light. This is pre-spring break so there aren't a whole lot of people there. If you go around President's Day weekend you will hit a lot of crowds. Based on what I know of other's who have gone in early February, the crowds were non-existent then. Rehabs: I would normally say you can count on 1 or 2 things being down but not a lot. However I would have said that about September until I saw this Sept's rehab schedule. There's no way of knowing no matter when you plan to go how likely there is to be a rehab. Since July is the busiest month for WDW, I'm guessing that any other month is likely to have more rehabs than July, but you get so much more done in February. Yes, hours are shorter, but again, you get sooooooooo much more done.
Hope this helps.