This is the kind of film where, whenever you find yourself laughing, you are simultaneously cringing at yourself for doing so. The heroes head for Hollywood to stop a bogus movie being based on them, fall in with an all-girl gang of jewel thieves, rescue a laboratory monkey and take random pot-shots at pop culture and Kevin Smith's other movies, all of which works with wildly variable effectiveness. The central problem is that, as portrayed by Mewes, Jay is such a monumentally repellent figure, with almost no redeeming features, that it would take a total sociopath to root for him. Smith's Silent Bob is actually kinder, nicer and a far better hero.
The same is true on the other side: Shannon Elizabeth's character is deeply unappealing, vacuous and vacillating, while Eliza Dushku and her evil jewel-thief buddies are easily as worthy of a spin-off movie as J&SB. There are moments of awe-inspiring inventiveness, but too many self-indulgent and/or totally lame ones. Smith has firmly established he can make this kind of film; it's now time for him to grow up and put his toys away. With Dogma, he showed he could - after that, this is a big step backwards.