Just saw the HP movie in Imax 3-D with the youngest and dh; we thought it so odd that it is advertised 3-D in selected parts (!) which translates into the opening ten minutes and that is it even though so much more would have been terrific in 3-D. Why did they even bother. Largest ick factor - they took our glasses back at the end - and put them back in a communal basket. Ew. Plus for the money we should have had jewel embedded ones.
I have read criticism that the movie offers no back story for people who have never read any HP books or seen the other movies - but apart from the creepy weird guy who was being good at being creepy and weird and then snored loudly from mid-movie on, I imagine most other viewers are long time fans.
My oldest son said the movie was visually stunning and he was right. It is not a film for younger children, but for those who have grown up with the books (and adults who love dipping into the world of Potter) it will resonate.