I have been quite a few times, yes it does rain but, it soon goes off and you will be grateful for it, it does cool you down. Here isome good tips for you.
1) when you get to theme parks, and you go through the main gate, go RIGHT and do the rides that way. For some reason everyone always goes left and the ammount of time you are standing waiting to get on anything is frustrating. A friend told me that tip and it works.
2) take a picture of where you park your hire car i.e I was parked in Mickey Mouse carpark , row 67. It would have took me ages to find the bloody thing cos all the cars look the same.
P.M if you want anything else, and have a fantastic time out there.
All the best you jammy B*****D