I went and saw it last night. It was a lot different than I thought it'd be, but I still liked it. The only thing I didn't enjoy was that I was sometimes afraid to keep my eyes open. It seems I can't handle much violence these days.
I loved the scene where Ofelia first used the chalk, though. That was so...I don't know. xD But it was awesome. GOT THE BLOOD PUMPING. Also, Mercedes was uber. Uber.