We went to the World around the 4th once, but never again. Knowing what is waiting for you is half the battle, though:
#1. It is HOT - not like "fan your face" hot, but like "surface of the sun" hot. Weat hats, bring water, eat lots of fruit, and take LOTS AND LOTS OF breaks. Sit by the hotel pool in the middle of the day and sip cute drinks with umbrellas while laughing at all the suckers sardine-packed in a three hour line for "It's a Small World".
#2 It is CROWDED - not like "gee, these lines are long" crowded, more like "oh my God, I turned around and lost sight of my husband" crowded. Use the fastpass system. Go to the big rides first. Do NOT plan on getting to everything. Do not be surprised by the lines, just plan for them accordingly.
#3 It is DISNEY - so if you go with a good plan, and the right attitude you're going to have a blast.
I hope this helps, and I really do hope you have a great trip!
