"He does seem to use this formula, but i find it interesting. Not many movies have a huge twist that you never see coming; "
Thats the problem, with his movies you inevitable expect a plot twist, the plot twist is what made the sixh sense so popular, it really invited you to rewatch it more closely, but it doesnt work anymore, the audience is tired and doesn't find it as interesting as with the sixth sense, sometimes it seems that his forcing a plot twist.
But what I really don't like about his movies is that he tries too hard, his focus on certain emotional aspects of a scene are really exaggerated, almost manipulative. I didn't like unbreakable for that reason, the same with signs, he seriously was trying too hard to make suspense, it was almost insulting for the viewer those long waits that he used to try to build it, which went along with the overuse of the "shock" scare (nothing...nothing... 1 minute passes...BAM! the monster/alien/whatever appears and makes you jump), I find that so lame, is such a cheap scare tactic. Probably the reason I like asian horror is that they almost never do that.