Months ago, a good friend of mine managed to get me a copy of The Descent on dvd, after I had read a lot about it on the internet. As a horror fan, I can definitely see why this movie gets such rave reviews, as its sense of dread and claustrophobia is overwhelming, the movie is shocking, tense and most importantly, scary, something which so many "horror" movies these days lack. It's might be rather slow during the first half, but it's most definitely worth seeing.
Only problem I find with it at the moment is that, obviously, people know there are monsters down in the cave, thanks to the stupid trailers showing them so much. I find that the monsters were the biggest surprise of the movie, and it's best to go see the movie expecting to see only six women trapped in a cave, getting hysterical and turning against one another by devolving into their most primal instincts in order to survive, and nothing else beyond that. When I showed the movie to a group of friends, I purposely didn't tell them about the monsters, and when the nasties finally appeared, it was a huge shock to them, and they loved it. Sadly, the magic of that shock is now gone for just about everybody.
Still, The Descent is an excellent horror movie, so I'm reccomending it to ya'll in here who like horror movies. The director was also the fellow who directed Dog Soldiers, a fun action/horror movie about soldiers trying to survive the onslaught of a group of werewolves, so if you ain't seen that one yet, rent it too. ^_^