[Demonique]

I agree that plot development and character development are essential too. Good acting is a must or it doesn't matter how good the plot is - the actors kill it. Atmosphere is also an essential ingredient- whether it is old, dirty rooms as in The Texas Chainsaw Massacre or Saw II, or empty desolation as in The Hills Have Eyes or Desperation, or dark eerieness as in Pitch Black, The Descent or Silent Hill. The Atmosphere is a large part of the movie. Sparse use of CGI is also preferred, real SFX are much better. Sound and picture quality is also important - you can often tell a cheap movie right from the first scene. A horror movie without it's share of gore and blood is just a suspense film. I like most endings, twists are good but I hate a movie that ends and sit there thinking "what? - that made no sense at all!". I likely won't watch a movie like that again. Underlying subthemes in horror movies give them more dimension such as Dawn of the Dead (the original). It was a horror movie with a little social commentary thrown in for good measure. A movie with that kind of depth also stands out.
OK - I'm done