I wish there were a way to give multiple ratings for this film, because I'm convinced there are at least three different versions of it. The original French (which I haven't heard), the English language version I heard back in the early 80's, and the American cast version. I KNOW this is different from the other English dub, because I distinctly remember lines which just don't happen in the US version.
In any case, maybe this is splitting hairs, because it's an awful film. All I can say in its defense is that I thought the version I saw back in the 80's had SOME redeeming qualities, whereas I couldn't find any at all in the version which has Bill Murray as the dragon.
The plot is simple and adequately explained on the profile page. Basically what happened was that Ralph Bakshi made the first X and R rated cartoons in the 70's, and this opened the door for people to bring us similarly 'adult' but horribly un-noteworthy movies designed to amuse high school students. Director Picha is the same guy who brought us 'Shame of the Jungle' (which is so obviously bad that I've never bothered to watch it), and the perhaps slightly better 'The Big Bang'. Frankly though, I'm boggled that this film got some sort of recognition at Cannes.
I'm of the opinion that the American voice cast probably made up the dialogue as they went along. A lot of the voice acting is crude and the lip synch is so bad sometimes that it seems more like narration than speech. Although I'll admit there are some funny lines, they can't save this mess - the US dub anyway. It's basically crude, in a crass, teenage sort of way, and really is a product of its time - titillation for teens in the early 80's.
I do suspect that the original version might be superior, and that there is a superior English voice dub out there somewhere, but this version doesn't deserve better than 1 star. Even with superior dialog, I still couldn't imagine 'Missing Link' being worthy of more than 2 stars.
BTW, Tony Hendra (Spinal Tap) apparently worked on the screenplay for this dub, and Christopher Guest provides some unspecified voices.