We brought our boys there when they were about 4 and 6. We also went with my parents. All of us had a ball!! There was something for everyone.
My husband, mom and me all rode Hulk...that was great. All of the adults loved Mummy. We really like the restaurants as well.
My boys loved all of the water features everywhere. We went in August so it was super hot. They played everywhere~ the spent over an hour running in a open fire hydrent in the NYC area. We actually had strangers ask to take their picture because they were having so much fun.
The characters were more current to them at the time. They loved Shrek, all nick characters, spiderman, curious george, cat in the hat. They were over Barney by then, but my 4 year old still liked the show.
US/IOA is also much cheaper than disney...tickets, dining, etc.
We went back to Disney about a year later and we had fun, of course, but we all agreed that our upcoming trip will not include any Disney parks. My boys were the first to suggest it....now 7 and 9.