Disappointed myself. Some great visual effects but I thought it was a missed opportunity. I watched it with a few friends from work and one of the young guys said "Wow, so cool! It broke all the rules!"... but IMO it broke none!
One of the main ideas behind film making is to get the audience to withold their disbelief (you need to get the audience to believe in the world they are seeing and get sucked in to it). I thought the main concept behind this flick was to give that real sense of 'this really happened', but the wooden acting, dodgy story and some other unbelieveable stuff (won't go into that as I don't want to spoil it) really pulled me out of the experience.
But... it's not all that bad. Like I say, it was a missed opportunity, and could have been soooo much better. Perhaps I had too high expectations when I went in. If you like VFX and other monster flicks (Who here doesn't?) it'll still be enjoyable