A near-masterpiece of slowly mounting horror and tension.

Rating: 9/10 (24 January 2006)

This is a truly remarkable film. The opening is full of subtle tension and the first shock of the movie is timed impeccably and executed very believably. This early first dramatic moment is essential in reminding the viewer that this is a horror film and creates a sense of anticipation that will be sustained throughout the rest of the film's introduction. The remaining half hour or so of introductory and character-building scenes is occasionally punctuated by a cheap shock - something which I think undermines the overall slow mounting tension of the rest of the film.
The film's strongest point is the way it portrays the fear of the unknown, of darkness and of confined spaces. Soon, these mundane, but very effectively conveyed, fears are eclipsed by the first glimpses of the lurking horror. This quickly brings on a change of pace and character in the film, with the amount of gore increasing considerably, though the fact that everything is shrouded in darkness mercifully hides some of the horrid details (though perhaps they are more strongly pictured in one's inner eye than when shown explicitly). The last part is composed of action-packed scenes punctuated by brief delirium, terror and anticipation. The final crescendo is triply surprising, though there is another cheap scare that almost destroys the cumulative effect.
The characters are very strong for this type of film and elevate it to something above almost any other horror film you might have seen of late. The musical score works extremely well with what is going on. The photography, camera angles and camera movements are executed flawlessly.
Apart from a slight overindulgence in shock scenes, which might merely be a matter of taste, and the fact that a few times the movie makers seem to underestimate the audience's intelligence, the movie is well worth watching. As an extra plus, for once the interactions between characters are important and add substantially to the tension.
Some very minor spoilers follow.
Firstly, the shock scenes. I am not sure why they had so many of them, but it appeared as though they felt that they just felt they had to maintain the interest of the more gaze-wandering part of the audience. On the other hand, some of the shock scenes were very realistic and useful. One such scene was the one with the crows over the corpse of the deer. Since I have once encountered a similar scene while walking around in the woods I could empathise with it quite a bit, though I must say it is not nearly as horror-inducing without the stench. But it does foreshadow the hidden threat very effectively.
The cave system itself is depicted wonderfully; it gives one a sense of awe in its juxtaposition of large and small dimensions. The climbing scenes are extremely believable as far as my limited experience goes, and the dangers of wandering around in dark places are portrayed nicely, though I am not sure it is possible to get severe rope burns while wearing gloves.
The creatures themselves are wonderful, though I would have preferred them to be almost completely silent minus gnawing and rending sounds, as were the monstrosities in the very similarly themed Lurking Horror.
I think that sums up my complaints. Do watch.