The thing that this film does best, and even then it's only through other faults, is ramping up the paranoia. As the characters sit around and discuss the situation as people around them keep dying, they try to figure out who it can be. Given that they're all aware they're in a horror film, and the fourth in a series of films which is doubling as a remake, they also realise that it will try to outdo the original, which means that those of us in the audience who try to second guess the film are kept guessing as to who's going to be the killer. I admit, I did figure out who it would be before the reveal, but it did have me guessing for a fair while, if only because the film keeps driving it home that you should be guessing.
Which brings us to...
All of the above can be written of as me reading too much into a genre film. I like the Scream films. Scream 4 was not as good as the first, but it was definitely better than 2 or 3, and it was very entertaining. The characters are stupid, and the film is just too self aware which means you don't end up watching a story, you watch people give examples of scenes from horror films and act them out
It is also still a clever film at some points, and I think some of its stupidity may come down to some inexplicably bad acting. I did love the moment when Hayden Panettiere's character is being menaced on the phone by the killer, and he's making her play the trivia game. When he says, “Name the remake–” she cuts him off by listing pretty much every horror film remake of the past ten years to shut him up. That was clever. The gay character telling the killer he shouldn't be killed because he's gay was insulting, and just not clever.
If you like the Scream films then you should be ok with this. But if you don't like a film where the self-referential scenes are more frequent than the scenes that tell the story, you'll be frustrated. It keeps on coming back to itself so much it feels a bit like it's walking on the spot.