The Big Lebowski suffers from what I dub "Mars Attacks! syndrome" - a very funny film that has all its laughs in one section, to the vast detriment of the rest. We follow The Dude (Jeff Bridges), aka The Little Lebowski, where a case of mistaken identity and an urine-soaked rug lead to his meeting a whole bunch of LA weirdos. There are some undeniably hysterical things in the first half of the movie - the introduction of Jesus Quintana (John Turturro); Walter Shopek (a superb John Goodman) a nutso Vietnam vet who is (inexplicably) The Dude's best friend and his hilarously unglued theories of the world; the sniveling Smithers-like behavior of The Big Lebowski's assistant; and the rambling opening narration of The Stranger.
It all begins to fall apart halfway through. The utter passivity of The Dude, while true to character, eventually becomes annoying. And the Coens set up an elaborate kidnapping plot which simply fizzles away. The second half of the film is dominated by gags that simply don't work - there's a band of German nihilists that apparently walked off the set of "Sprockets", and a long elaborate coda involving the death of Donny, The Dude and Walter's bowling partner, that falls spectacularly flat.