Maybe it wouldn't be so bad if you discounted everything terrible about the ride that everyone else has pointed out already (I think they did a pretty good job at theming the physical sets, there's something I really enjoy about them) but I just cannot get over how much of an ear sore it is whenever they shoot out the steam effects. The ugly PS3-style graphics don't help either, nor does Dom being about the same size as the helicopter. I went on it with friends yesterday and everyone pointed out how badly it hurt to just listen to the obnoxious explosions and gunfire left and right, as if there's some "story" that just ends with you randomly in a warehouse for... a party?
The thing that makes this ride worse than other painfully loud rides like Transformers is that the ride vehicle isn't at all dynamic and I can hardly tell what's supposed to be happening most of the time. They really botched that voice over of the FBI agent, it's incredibly distracting how off it is (although after re-riding Forbidden Journey, somehow those final screens where Harry/Dumbledore are talking to you are worse.)