I'm going to post a full-length review of it later this week, but I agree with you overall. Most of the weak points of the first movie (the kids' acting, too-cheery tone, over-the-top-score, and cheezy CGI) are notably improved in the sequel. I was definitely impressed with the improvements in set and prop design - everything has more of a dark and sinister look to it.
I hate to say that the biggest disappointments were the script and the pacing, which surprised me because Steve Kloves is a great writer. The script removes too much information, including the best clues about the identity of the one who opened the Chamber of Secrets, leaving the villain to do too much explaining at the finale, causing it to drag a little. If they had shortened the interminable denouement by about 10 minutes, there would have been plenty of room to include the important facts removed from earlier portions (e.g. details about Hagrid's expulsion, Ginnie Weasley wanting to talk to Harry about something, etc.) I'm guessing, though, that the way-too-huge finale was the idea of director Club-You-Over-The-Head Columbus and not writer Steve Kloves. I am SO glad that Columbus is out for the next two movies - his replacement, Alfonso Cuaron, has a talent for depicting frank and realistic sex scenes that may just come in handy.
Also, I wasn't a big fan of the long trench sequence in the Quidditch match, if only because the Snitch shouldn't be allowed to leave the playing field. I am aware, however, that complaining about that makes me a total nerd. So sue me.
