It would have benefitted greatly from taking it a little more easy. Cut away a couple of the monster scenes and have some breathing room. A little less dark terror and a little more whimsy. Its queue line might be the greatest ever built, but the ride experience itself is too dark and noisy for me to really like. Gringott's faired a lot better in this regard.
I find this to be a problem with a lot of Universal dark rides.
They're all action, action, action, and no relief.
I think the Transformers ride is the worst for this. The first time I rode it I had absolutely no idea what was going on. There was way too much happening.
I find that these rides work better when they start off relatively calmly and then follow the "something goes wrong" storyline.
Perfect example of doing it well is the Jurassic Park River Adventure. It starts out as a gentle tour of the dinosaurs, then it goes wrong, and the action builds to peak at the end of the ride.
Both Potter dark rides would have worked better following a similar formula in my opinion.