Harry Potter was fine, but I don't think it'd make much sense if you hadn't read the book. The narrative was very choppy and disorientating.
My major complaint was with the overuse of CGI. The low point was when they showed the scoreboard for the Quidditch match - it would have been lovely if they'd had a handmade board, something mechanical, you know, with brass and wood, but instead it was yet another boring 3D monstrosity done in a hurry (by the look of it) on some workstation. Yeccch. Just because you can do everything on a computer doesn't mean you actually should.