It's crowded, but very manageable. Get there early and you can grab a FP for a popular ride and then ride another. When we went during President's Week in 2006, we encountered wait times along these lines:
60+: Space because it was relatively new
45-60: Indy, Peter Pan, Screamin, Soarin, Alice, Splash, Dumbo, Monster's Inc. (only because it was a month new. Now it will average around 15 minutes)
30-45: Star Tours, Autopia, GRR, ToT, Mulholland, Matterhorn
15-30: PotC, BTMRR, BLAB, Mr. Toad, Mad Tea Party, Roger Rabbit, Gadget, Maliboomer
Everything else was close to a walkon. HM was closed.