I have. I was there right after it opened. 2 hour waits to get into the section, an hour wait for Honeydukes, 120 minute waits for FJ, people up your butt like a giant wedgie. Yep, I've been there, done that. I still loved it. Of course, Im a Potter nerd, I used to wait in 6 hour lines for a midnight book release, even with a pre-order done 8 months in advance.
Crowds and lines are par for the course in this fandom sadly. I honestly think if you put a bunch of seasoned hard core Potter fans up against a Black Friday crowd at Walmart with a $5 iPod sale, the Potter nerds would be the ones who come out unscathed and with iPod in hand first.5-7 day camp-outs for front barricade positition at movie premiers are common occurances.
Not that Im disputing how insane it was for you, I've read about the crowds the week you were there, and insane is correct. I'm just saying, that for some, insane can be handled. But really, I don't think the OP will experience that considering when they are going so it should be ok for them.
The amount of people packed into that area was probably violating some kind of fire regulations. I couldn't tell you how long the ride lines were because we couldn't get close enough to see. I figured it would be busy, but it was beyond manageable. There are 100's of reviews on Tripadvisor from people who were there at this time saying the same thing. Universal needs to come up with some way to manage this. For us WWoHP had no bearing on our trip, we would have been going if they never built WWoHP.
On the positive side for those WWoHP fans from what we could see the place looked pretty cool. The Attention to detail was evident even from a distance. If you can make it there on a day when it isn't like this I'm sure you will have a blast. Unfortunately for us this is the only time of the year a major vacation like this works.