People who didn't like signs didn't understand it, it is basic philosophy. The problem does not lie in the movie, but in the viewers ability to relate to the movie. It is not possible to say the movie was bad, becuase it was just a bunch of events, it is how we relate and react to those events. Those things lie in the viewer. So all those who say they didn't like the movie show that they just lack the ability to properly relate to it, as being "bad" is not an attribute of a thing, in this case Signs, but rather put upon it. It works the same for all types of things, art, music, books.
Well to go back to toic, M. Knight is just the most unbelievable producer i have seen. There is a feeling that is given off by his works that go beyond anything else. They feel real. Would Aliens really look strange, we look like a bag of flesh with 4 appendages sticking out. I believe it is safe to say that M.Knight, behind a game, would just totally redeffine whatever genre he tackled.
Anyway, i hope i have shown how these people who claim the Signs is bad, as people who speak without understanding of the nature of the things they talk of.