Hmmm, I was going to pipe in about my thoughts on Gringotts before and didn't but since you asked, I figured I'll comment on my experience:
I was a little let down with Gringotts. Don't get me wrong, a fun ride, but seemingly overhyped to me. I certainly wouldn't wait hours to ride it. Some things I didn't like:
1. A lot of people remarked that Uni was aiming for more family friendly with the ride. If that was their goal, IMHO they missed the mark. My kids (who generally love thrill rides and are fine with dark rides) were pretty scared after riding it and it struck me as very similar to multitudes of other rides at Uni in terms of intensity. It's probably that my standards were off, but I thought the tech was going to be used to make the ride more, I dunno, immersive but not as thrilling/intense.
1b. Also, I know they want to keep in theme, but couldn't they make the baby swap room a little brighter/less scary? I mean, you have people in their with young kids and it's cramped and dreary.
2. I feel that to really enjoy the ride, you have to have pretty good knowledge of the HP books. I read the books, so I was familiar, but never saw the Deathly Hallows movies. I found the ride to be difficult to follow/enjoy without being acutely familiar with the source material. FWIW, I think Forbidden Journey is much more accessible to those uninitiated.
3. Related to #2, but it was another ride at Uni where I feel you don't get a chance to "breath" and absorb as you are watching. The Tech is very impressive, but the pacing is so frantic that it's tough to have your mind really appreciate what you are experiencing. IMHO, there needs to be some built in (brief) lulls in all the action to gather things. It doesn't help that whenever your not watching a scene on an (impressive) screen that your being whisked around quickly.
4. The dialogue was difficult to hear well, which made the plot of the ride more difficult to follow (see #2 again). I guess this is the audio issues that were mentioned. (Admittedly, I tend to have difficultly understanding British accents sometimes even under more ideal conditions.)
Again, I'm not trying to disparage the ride, which I thought was very good. But after all the hype, I thought it would be a more transcendent experience to me. I'm still waiting for Uni to produce a better ride than Spider-Man, which is IMHO their gold standard.
One thing I'd really like to see for any HP addition in the future is to not make it about Harry Potter. One of the aspects that I think is really cool about DA and Hogsmeade is that you are experiencing visiting the Wizarding World. That's why the shop windows, restaurants/food and especially the wands are awesome -- they are about experiencing the cool, different world of wizards without the guest being burdened by having to know the specific tales of Harry Potter. I might be alone in that sentiment, though.