We were there last Easter and the crowds on Easter Sunday were BIG! The numbers didn't dwindle until evening and then there were considerably less people. We actually felt like we could breathe. Seems that people had to leave to get back to work on Monday. We weren't leaving until Monday morning so we stayed until the park closed. We really enjoyed our last evening! Have fun!
Extremely crowded. Expect hour long lines for many attractions (Space, Indy, Splash, Nemo, Peter Pan, etc.) starting late morning and lasting until late evening. Your best bet is to arrive super early and use FP a TON!