Those who appreciate Terry Gilliam as a writer & director will likely enjoy this movie. If you have no idea who he is, then you should probably avoid this. You’re sure to figure that out if you read a lot of the other reviews listed here.
If you’re expecting the same type of zany-absurd-yet-intelligent humor as a typical Monty Python movie or Flying Circus episode, then you’ll be a bit disappointed. There really aren’t any laugh out loud moments in Jabberwocky, just lots of chuckles at the dry humor and subtly clever, funny scenes. The only times you pick up any Python-esque humor is when the scenes hit you with the grotesque (which is one of their trademarks).
Kudos to Gilliam for capturing the look & feel of the filthy, grimy, run-down Dark Ages (obviously our perception of what we think it was probably like), especially on such a low budget. Michael Palin does an excellent job as naive-innocent-hopeless-romantic Dennis. (As a side note, it struck me as an odd choice for a name since it isn’t British, although I think it was meant as a subtle joke. Palin also played a ‘Dennis’ in a brilliant scene in Monty Python’s Holy Grail, which also took place during the same time period).
The bottom line is watch this if you’re a Gilliam or big Python fan, but you’ll likely regret watching it if you’re not.