Monty Python has put out a couple thousand movies and skits. A couple are bound to be good. And that's about it.
Holy Grail is/was their first movie, and no, they've only put out 5 movies if I am remembering correctly. Their half hour series Monty Python Flying Circus lasted four seasons and 45 episodes, was and still is some of the funniest stuff ever. They simply changed the face of comedy, and most of the comedy you young fools like such as Dumb and Dumber comes directly from their influence.
The original group of Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones, and Michael Palin is still one of if not the most prolific grouping in humor history, only the cast of SNL's first two years or so could come close.