I saw this one yesterday and I'm torn on it. I thought the first hour or so was great with a good amount of atmosphere and dread building with each new discovery. After that, it feels like it went on generic horror autopilot and had all of the things I had enjoyed earlier sucked out of it.
A number of folks mention liking the score, but I'm not in that camp. I found myself getting distracted by it too often. It telegraphs some decent scares that wind up not having any impact because of it.
All of those criticisms aside, it's definitely worth a watch.