One thing's for sure - - Ryan Reynolds was born to play the stereotypical idiotic American - - look at him burn his fuel like there's no tomorrow!
Seriously,
Buried is pretty darn good as "Man in a Box" movies go. Especially good was the camerawork, essentially staying within the confines of the box, or occasionally cheating in very creative ways. The screenplay was also quite good...
except when it was bad - - eg: the fuel, the snake (!?)

...working within the constraints of the setting quite nicely to make a watchable film.
Buried isn't afraid to use a totally black screen or a silent soundtrack to set the scene.
However, on the negative side, was the aforementioned fuel wasting. Yeah, yeah, I get it - - it was a fun part of the lighting scheme - - how do you rationalize that a "Man in a Box" would be able to light himself sufficiently for an hour and a half to make a movie? - - but, the survivor in me, couldn't get over the ridiculous waste of resources:
Air: He kept saying he couldn't breathe, yet he thrashed around, burned oxygen with his Zippo, and repeatedly screamed into the phone.
Fuel: Lighter fluid, battery power in the two cellphones and flashlight, the two glow sticks.
Alcohol: When he wasn't slopping the tiny flask's contents down his face, he was using it with far more flagrant stupidity on the spoiler ^ above.
Contacts: This is the least bothersome - - the guy's just a hothead - - I could buy that he would foolishly burn off friendly contacts in such a time limited scenario. Ditto on him frittering away his meager bargaining chips.
Sadly,
Buried kept making me think outside of the box with those concerns - - I want to see a truly great "Man in a Box" movie one day - - but
Buried isn't it. I'll rate it a 3 out of 5 on the "Man in a Box" movie grading scale. I'd even like to see this same director, with his obvious talent for visual framing, try it again with a screenwriter more worthy of his efforts.
Nonetheless, as a movie in the broader sea of movies, I will rate it quite a bit higher - -
Buried is a damn sight better than most of the flotsam I've seen drifting through the megaplexes this Fall...
...and if nothing else, I have to commend it on it's boffo ending - - Bravo!!!
12 out of 5.