It has its moments (and the graphic orgy is slightly inspired), but mostly it just reminds you of every stoned bro rant you've ever heard, from the sexual, to the political, to the "what if food had feelings" variety. (And maybe, for that very reason, it has some slight cultural significance.)
The trailer promised more and seemed a lot more interesting. There are a number of good jokes, but overall, it's nothing more than a journey story so much like many others, where imagination is the best thing, regarding the parallel between the products and the cultures. The promise of the humour of things being eaten, quickly slides easily to the quick sexual joke which is funny, but can't support the plot.
A handsome film to be sure, but Seth Rogen is far out of his depth in trying to tackle animated surrealism. He ultimately can't really settle on an internal logic, which makes the fourth wall-nuking ending connote as insultingly lazy. That's not even getting into the film's excess of bodily humor, which peaks in a cast-wide orgy that adds to the questionable implications piled in the corner.