Boyle somehow manages to pear this film down to such minimal elements (the majority of the film is Ralston in the cave), and yet he builds something that is engaging. I had reservations about an hour and a half film that primarily takes place in a cave while its lead character is stuck under a rock, unable to move. Boyle uses the first twenty minutes, or so, to get Ralston to the cave, in which he meets two girls and has fun with them, showing them little places on and off the trail, giving them a tour of parts of the park most people probably wouldn't see, but once they break off, it's a matter of minutes (in screen time) before Ralston is trapped. The rest of the film plays out in a feverish attempt to figure out ways to extract himself, and flashbacks to the past. Franco delivers a solid performance, and this role was, in a way, tailored to his flamboyant personality.
I feel like I can't say much about the technical aspects of the film. The vista shots in the park were gorgeous, but, since the majority of the film takes place in a cave, its kind of hard to, otherwise, comment on something like the cinematography, and the two trail girls (played by Amber Tamblyn and Kate Mara) have so little screen time I don't feel like I can really comment on their acting. The film felt solid, though, and I think any film that takes place, primarily, in a cave, with its protagonist stuck in one position, and can still keep you interested is definitely worth watching, though I think this one will probably end up with others like Millions and Sunshine, where it will not exactly join the "essential" Danny Boyle cannon.