There's been lots said about this film in relation to Python on IMDb already, so I won't bother making comparisons. Jabberwocky is a messy, but extremely entertaining film, full of sly satire and crass scatological slapstick. It's an extremely grotty movie - everything is squalid and grotesque. Even the King's palace is falling to bits, and all the characters are either stupid, violent, or both. The film spends a long time farting about, exploring various daft notions and barely-related events, before getting down to its titular business in the last 20 minutes or so. But there are some sublime jokes in there and it's an interesting Gilliam "period piece". You can see the twinkle that later grew into the likes of Time Bandits, Brazil, Baron Munchausen etc.
Watch out for Terry Jones doing a ludicrous cameo as a poacher, pulling some of the most ridiculous faces ever seen on screen.