They made that movie just to capitalize on the 3D trend and it shows. I'm a big fan of the series but I agree that that movie blew a big one. Just an all around bad movie.
I admit I was high when I saw it but I felt lost the whole way through and not in that like Sixth Sense kind of mind fuck way but in the "WTF IS GOING ON?!?!" type of way. It was just...just...stupid.