Saw it when it first came out, and it was a good movie (certainly better than the last Harry Potter) but not "great". It tried too hard to be a "spectacle" in it's own right rather than a great movie.
There were also a couple of really nitpicky, annoying things that I just couldn't seem to look past.
1) The little girl who -- no matter what was going on around her -- kept this ear-to-ear "I have no idea what's going on" grin. I know that's a matter of a new, youthful actress and don't AT ALL intend to hold that against her, but it was distracting to see a film transition between the older brother and sister shouting "war!" to the little girl sitting there grinning like she just "ate the cat".
2) Perhaps it was the translations to the movie, perhaps it was the accents of the actors. I knew nothing of the book, but had often heard of "Osland" (oz land, or how I would pronounce it). Actors in the movie kept constantly referring to it as "ass land" which, for a kid's movie, bothered me greatly.