First of all, there aren't a ton of good Horrors out there that are truly original. I'm not saying this movie is one of them, but that lack of originality shouldn't be the reason to give any movie a lower score. Bringing fresh ideas to the Horror genre is difficult, mostly because it's difficult to find new ways to scare people. There aren't a ton of moments that make you jump, but I think the genre isn't really about making people jump anymore. Audiences have gotten good at predicting when these moments happen.
Where this movie does well, along with the rest of my favorite horror movies, is atmosphere. For me, having a dark, creepy atmosphere is far more important to success in this genre than getting people to leap out of their seats. The shaky-cam, found-footage style isn't that much of an issue for me either. Actually, I think still does a good job portraying realism, despite being a bit disorienting and annoying.
Story-wise, I'd say it's pretty unique. How many other horrors involving descent into the earth to find historical relics can you think of off the top of your head? One, two maybe... How many horrors can you think of off the top of your head involving a haunted house, a possessed child or doll, exorcism, a guy with a mask, or a cabin in the woods? 100? Not to say this is bad, but I'll gladly welcome anything outside traditional horror settings and scenarios. It does dip into the realm of ridiculousness as some points, but nothing too over-the-top and far-fetched for the situation. The acting is good and the characters are believable for the most part. I would have cleaned up the final act a little bit more, but it was good enough to keep me satisfied.
Not sure what the critics are bashing it for. If there is anything to really complain about it's not this movie, but the genre itself. That being said, lower your expectations and you might like it. I'd give it a solid 7 out of 10.