We went 6th April last year for 2 weeks (not Easter) and found it really busy, compared to our previous trips in May and November. There were lots of Spring Breakers around, and the queues for rides were quite long, especially on the bigger rides ie Test Track in EPCOT had a really long queue and all fast passes were gone, but luckily it was a late opening for on-site guests, so we got on that way - twice in a row!
The weather was not as hot as we had expected, but I think we had some freak weather, as lots of people were buying blankets and fleeces from the shops in the evenings, we had quite a few evening with really chilly winds blowing. We did have other days when it was really warm though, so it was a mixed bag, but not wall-to-wall heat.
Also, must mention that we didn't get to see Fantasmic, the arena was full an hour before the show!

If we'd know how busy it was going to be, we'd have booked the Fantasmic Package - we did this for New Year's Eve though, so we got there in the end!
