And they missed a lot of the really funny bits like clearing Grimmauld Place of creatures etc, the screaming portraits except they left the bit where Tonks knocks something over in the hall which wakes them up... why??
Ridiculous to not include the prefects part as it changes the dynamic between the friends.
Cho did not grass them up to Umbridge although it tied in neatly with her and Harry falling out.
It was a great film if you haven't read the book or if (unlike me because I'm a pedant ) you can distance yourself from the book in order to watch the film!
It is far scarier than the other films IMO and the plot harder to follow for the youngsters, there were quite a few children last night ranging from about 6 on, none of them seemed to be too traumatised but it does depend on your children and how sensitive they are. If in doubt talk to someone who has seen it and knows your dcs or go on your own first.