Rated R for retarded.  Not much to say about this one.  Although there are several very funny parts and the play off the main movies is funny, the movie seems like it lasts only about 30 minutes.  The main movies spoofed are The Grudge and War of The Worlds.  The movie, following in the prequels steps is on par with the quality of the others, but takes the likeness of the originals to the next step.  I'm not sure if you'll like Scary Movie 3 better or not, but if you don't like this series, stay away.  If this is your genre, then I'd actually suggest waiting on Blockbuster.