I haven't seen this movie, and I feel that from Roger Ebert's review that I don't want to see it, but many of the "reviews" I'm seeing in this thread sound about the same:
"DERF! Darez no m0nztrz N like stuf!!!!1! Itz noy a horer moovy!!!11!"
Seriously, though, not to step on anyone's feet here, but if you go to a movie to see scarey knife weilding dudes jump out from the darkness, you're probably not the best person to give movie reviews.
I'll break down M. Night's movies that I've seen for you.
Sixth Sense:
A bit over-rated for M. Night's first success. He has a deffinate knack for making characters that we could care less about, and this is probably the "dumbest" movie he's made. What I mean by that is that the underlying theme really wasn't there. It's the closest to a horror/thriller movie that one can get in a Night movie. I'm thinking this is why it sold so well.
Most notable for it's "artsy" use of color, the color itself doesn't really have any metaphore to it at all. It's more like Night wanted that post-modern film feel to it and added a "ghost metaphore", no pun intended. So what exactly did the red represent in the film? Nothing really...just something to catch your eye so you'd remember it later.
Unbreakable:
My least favorite movie of the three. Night thought he had the method for a blockbuster down, but he took all of the wrong aspects from his first movie. So now he has a movie where the characters are so bland that he expects you to be frightened by their eerie nature, but all we the viewers feel is boredom. This is also where we first see Night's true weakness: his lack of humor. He takes his movies so seriously that he expects us to be enthralled by characters that speak in monotone voices about things that we might find scary.....if we were paying attention that is.
This movie did have one of the best individual scenes in it of almost any movie I've ever watched: The train station scene. Here Night gives us our first taste of substance: a deeper look at humanity. Just by brushing against "innocent bystanders" we see the true darkness in the hearts of men, and it really makes us think about society.
More use of pseudo-artsy color, plus an added touch of pseudo-artsy camera work that add nothing to the film. (Filming an entire scene from the reflection of a blank TV screen is annoying, not enlightening. Likewise, if three-quarters of the scene's visuals are consumed with panning across a train's seatback, you've lost your audience's interest.
Signs: Tada! A movie that's actually ABOUT something...besides spooky crap. (BTW, if you wanted to see more scenes with aliens attacking, rent Independence Day...and if you think ID4 was better than Signs, you shouldn't invest much of your effort into movie reviews) Night's last movie (despite some people thinking it was wonderful

....) didn't make a big box office splash. So he decided to actually give his characters...well, character! So now we have some characters who actually show emotion; add in a suprise ending twist that actually had something to do with the movie's theme (which was Gibson's reassessment of his faith when his wife's predictions made themselves clear, as opposed to "Suprise! You're a ghost!" or "Surprise! I'm your arch nemisis!")
There's a noticable lack of artsy crap, and for once we feel a bit of humor in the drama. This is Night's best movie as far as I'm concerned.
So now we have this new movie that returns to the melancholy droll of "who cares"ness that takes itself way too seriously, returns the artsy crap, and has a significantly less important theme. (I'm not too sure of this, but it has something to do with love, no?) So tell me this: So if Night's first two movies were wonderful, why is this movie, which returns to their same methodology, total crap?
Hmmm......