No, fool. The Descent. And, yes, you should see it instead. It's not only a better movie overall, but it's also scarier.
For about half the movie, you will be asking yourself, "I thought spectralbovine said this was a horror movie?" It is. Just wait. I tell you this in advance so you don't let impatience get in the way of appreciating the first half. I think the fact that it takes its sweet time getting to the actual horror part ends up making it scarier because it feels so real. Everything is grounded, including the characters. The character dynamics are important as well, and you really get the sense that all these women are good friends. Some are more fleshed out than others, but no one is a one-note caricature. And because they feel like real people, the psychological component of the movie works as well. Plus, the movie assumes the audience is smart enough to understand the psychological component and character dynamics, which is quite lovely. This is the sort of horror movie that makes you look at how real people react under extreme circumstances.
As I said, the movie doesn't deliver scares for a while, but once they start coming, they keep coming, and the tension never drops. The camera work puts you right in there with them, cramped up in dark, enclosed spaces, fighting for your life frantically. At times, the movements are so quick and the editing so fast that you can't exactly tell what's happening, but it works because, if you were in that situation, you wouldn't be able to tell exactly what's happening. You would just be trying to stay alive, grabbing at whatever was around for a weapon, keeping the cave beastie from ripping your throat out. And the tangibility of the beasties and the intelligently constructed air of mystery surrounding their existence makes them much scarier than the flickery ghosties in Pulse.
In addition, as zenkitty_714 points out in her excellent review, all the main characters are women. There is one male character of note in the entire movie, and he's not in the cave with them. The protagonists are all strong, adventurous women. A couple are total badasses. There's a power shot worthy of Joss, very similar to Buffy's in "Anne" and River's in Serenity. It's worth noting, isn't it, but it's also sad that it's worth noting, as Joss said in his Equality Now speech.
This is a quality horror movie, people. Well crafted in all the ways you expect from a regular movie. It's being hyped as one of the best horror movies in years, and, despite not having seen that many horror movies in recent years, I would probably agree. It's not your typical horror movie, in any case.
One final note: if you've heard about this movie at all, you've probably also heard that they changed the ending for the U.S. release to make it less "dark," but that doesn't mean it's a happy ending by any means. I agree with the director that it's a "happy" ending the way the ending of The Texas Chainsaw Massacre is (and that movie does have a pretty fabulously creepy, chilling ending). The way I interpreted it, I really liked the ending.
So, go see The Descent. Especially if you're about to go into some caves.