I just got back from this. Pretty amazing overall in my opinion.
I was actually surprised at how good a look you get at the monster. I had heard it was just glimpses here and there, but you get a really good look about 4 times.
Anyway, ignoring everything else, the movies presentation was pretty fantastic. I'd recommend that if anyone is planning on seeing it, see it in a theater. I don't think it would have the same effect otherwise. Despite what you think about the rest of the movie, it's very entertaining. They do a really good job of making you feel as if you're right there where all the shit is happening. Otherwise the characters were pretty good and I liked the plot. There is something about it that I can't put my finger on that rubbed me the wrong way, but otherwise it was awesome.
I've never seen Blair Witch so I can't compare, but this movie is definitely a ride.