so, i saw it, here are my two cents:
very good movie, i totally agree that its much darker than the first ones...
the dementors were so cool, first i thought "oh, nazgul!", but after a few seconds you can see that they tried to make them looking different and they made it good.... yes, they ARE scary... ;)
i realised the hut-thing too.... but all the terrain around hogwards looks a little bit more detailed and more realistic, they made a real landscape (in the previous movies i had the impressions that hogwards was somehow "out of space")... i hope, they won't change the surrounding in the next movies anymore....
oh and the bus drive.... yeah, it was sooo funny!!! one of the best scenes of the whole film.... :D
the last minutes were a little bit complex and somehow confusing, especially for the younger audience... but maybe i thought this because i drunk some beer before entering the cinema... ;)