This movie grabbed me by the throat in its first five minutes and kept me pinned down for the duration, frightening the breath out of me and pumping my blood full of dread juice. The Descent is aerobic in its scariness. It's working feverishly on four scare levels (yes, four). The first is phobic: A group of friends go spelunking. They worm their way through tiny passages. I'm not particularly claustrophobic, but this movie ignites a compounding panic by setting almost all its action in tight spaces.
The second is sociological, for lack of a better word: A series of events throws the group into discord, which layers more strain on an already tense situation. The third is predatorial: There's unexplained phenomena in the cave that start to add pressure to the dangerous situation in which the group finds itself. The fourth is mental and spiritual: This aspect reveals itself at the film's end, but has been building all along. It deepens the psychology of the film, and makes possible the devastating final sequence.
The film looks great -- the visuals are vivid and kinetic, the colors are dangerously beautiful. It's seductive-looking. The cave scenes were shot all on set, and it's a seamless and terrifying world. The cast, which obviously was put through hell during shooting, is perfect -- especially our lead protagonist, Shauna Macdonald, who combines beauty and brawn and grief better than Uma Thurman did in the Kill Bills.
I like a good scary movie, but when things tread toward the "horror" end of things, I get wary. A plot reliant on gore isn't appealing to me. It's disturbing that movies like Saw and Hostel do bully business at the box office. There is plenty of stylistic and nauseating gore in The Descent, but there is much more at work. I won't spoil the particulars. This is a movie to be experienced. It's an adrenaline rush. It will stick with you for a long time. The dread will linger.