I hit USF/IOA a few times a few years ago and my impressions were:
- They're nice theme parks
- The older attractions are heavy on the cheese / not quite up to what Disney puts out.
- With Harry Potter they seem to be turning the corner and really trying to step up the game.
Some of the stuff left me wanting: The Mummy, Twister, & Poseidon come to mind.
Other stuff seemed like good theme-park type attractions: Earthquake (or whatever it's called), Bluto's Raft Ride (by far, the best raft ride I've been on - I love it that you get really wet), Men in Black, E.T. (not great, but standard theme park stuff), The Hulk, etc.
Harry Potter and that whole land over there I thought either matched or beat Disney.
Some of the simulators were really good with The Simpsons Ride, Spiderman, etc.
Dudley Do-Right's Rip-Saw Falls (I think that's the right name) was good but with one of the oddest ways I've ever seen to put humans on a ride. Keep your body stiff and kind of slide in. So weird, awkward and uncomfortable. The ride itself is good, though.
The other oddity which I was kind of excited about riding was Dueling Dragons. When I got on it it felt really light on the theming. The loading area is OK but the ride itself felt like it was just out on some ill-kept empty lot which may be a water retention pond for heavy rain. They also stopped running them in synch which took some of it away.
Probably the biggest difference for me is that at WDW I feel like away from it all and immersed in Disney stuff. IOA/USF felt like I was at a theme park (hopefully that make sense). Not bad, just kind of left me wanting it to be "more".
So, to me, it's kind of a mixed bag at IOA/USF, but if they continue doing things on the scale and with the quality of Harry Potter, I'll be going back. Even now I'm intending to go back for the Harry Potter section opening in USF.