Hey, when they are still getting in for free - TAKE THEM!
Seriously, my DD loved it this Jan at 21 months. She's a little shy but still had a great time. DS when for the first time at 2.5 and it was so great. He is that kind of kid though - doesn't scare easily, etc. This year he wants to do all the BIG rides (Thunder, Splash, etc).
DD and DS both love the videos we taped as well. We have to transfer them to DVD soon before they wear out. So long as you can afford the trip then go. For all those people who say they won't remember it weren't speaking of my kids. They both remember a ton of it. Will they remember it 10 years from now, not sure, but by then we will go again!
Have fun!!!
Oh yea, take a mid day break (very necessary)! Also, we did not stay out much later than we would at home. Keeping the home schedule saved us from major breakdowns.