Agree with pretty much everything you said, except I liked it quite a bit. I put it as #3 in my order of liking in the series. I liked 1 and 2 the best, as they set the scene and we got to see all the cool new things, like magic, and classes, and quidditch, and the original Dumbledore, whom I preferred, and the kids wearing their uniforms.
One of the things that bugs me the most about these movies is that the kids never wear their robes in the later movies. I get that the actors don't like them, but it's a big part of what sets these stories apart from normal movies about high school. Not to mention, part of the humor is that these great wizards can't dress like us to save their lives, yet as kids they run around wearing GAP everywhere? What sense does that make? If you don't want to wear the costumes, don't be in a movie where they're significant. Otherwise, what's the point? Sorry, rant over. Back to our regularly scheduled programming.
I also liked the scene in the cave. However, I was surprised that this got a PG when the last couple were PG-13. I thought that the cave scene was every bit as scary and violent as some horror movies from when I was a kid, especially when you include Harry basically torturing AD with the potion. Not to mention AD's nasty hand that kept popping up. I know that kids are "older" now, and most 11 and 12 year olds could handle this fine, but I still thought it deserved a PG-13. I saw a LOT of younger kids in there that looked AWFULLY frightened at several points, and a few of them cried.
My question is, where are they gonna split the seventh book for the two movies? That would be an interesting thing to debate. Good split points.