Two things I enjoyed most:
- the performance of the guy playing step-father of Harry Potter; it was however a recycled caricature
- the chess game, which had great character design and animation; it's a pity it was mixed with substandard editing, with shots repeatedly cutting to the kids; also, the kids didn't fit well in a sequence so scary
Most anything else is just standard, which is the sort of thing that made it mysterious to me why the book/movie series has had such spectacular success.