We were there Monday 2nd April 07 and it was very busy but of course that was a big weekend. The consensus here I think would suggest that Fri - Mon are the busiest days with the mid week days quieter. Be sure to have your tickets bought in advance and not like us spending an hour queuing just to buy ours ! It was 11am by the time we actually got in and of course it was very crowded at that stage. Juat have your homework done on what you want to do, get your fast passes etc...