We just returned from a visit to IOA. There are many problems.
The attractions are sporadic. You can walk through Marvel and find a pretty decent amount to do. If it's a little chilly or it's raining, Toon Lagoon is a giant waste of time and space. Jurassic Park screams wasted potential. Over at Lost Continent, Poseiden's Fury is a colossal bore with one pretty darn cool special effect in my opinion.
The rides themselves are poorly maintained. As pass holders, we visit somewhat often and find broken down rides all the time. Just today we were trapped on Spiderman for 15 minutes with no explanation of what was going on. When the ride fired back up, it was without the special effects, but the car went through the same motions with the house lights up. Very bizarre indeed.
Another poster remarked the rides cater to one demographic. I think that's half true. The rides cater to two demographics: big thrill seekers (Dueling Dragons, Hulk, Spiderman, etc) and....LITTLE KIDS (Dr. Seuss, Jurassic Park area). There's no real middle ground. Case in point, my wife doesn't like big roller coasters. Therefore our time at IOA consists largely of me waiting in line alone and her shopping around.
The staff comes off as rude, at least those we seem to encounter. I'm not looking for someone to wipe my butt for me, but no one makes eye contact or thanks you.
And are we the only ones not thrilled with the layout of Universal itself? The parking lot is like walking through Atlanta Hartsfield / Heathrow / Frankfurt / O'Hare airport. Once you're done with that, you have to go to the far end of Citywalk to get into the park. At this point, you just want to get on some friggin rides, so maybe you're more inclined to turn right and go to the "Studios" instead.