"Clerks II" is one of the worst movies I've seen in theatres (mostly because I'm super picky about what to watch in theatres). I liked the ending, the dance sequence, 'porchmonkey', and all the Lord of the Rings bashing, but I simply don't think there was enough there to justify a full-length feature. I know for a fact that the Lord of the Rings bit was something he'd already done like stand-up comedy when touring, so it's just a lot of ideas he had stuck in a movie that weren't really worthy of one. The whole donkey show bit in the middle was a totally unfunny and boring waste of time, and the movie's 'insights' about relationships were shallow and implausible.
It's a huge step down from "Clerks", which was packed to the gills with intelligent insights, basically justifying its existence for every minute of its runtime. It's like Smith took all the funniest and most important observations/insights he'd learned about life and work up to that point and crammed them all into that movie and they were integrated into the situations and dialog perfectly. It's as hilarious, witty, and insightful as "Clerks II" is unfunny, unnecessary and empty.
I never wanted to see one of his movies again after wasting my money going to the movies for that, but "Zack and Miri" won me back. I've only seen parts of "Jersey Girl", and I will never watch "Cop Out". I forget everything about "Mallrats" except the line about farting and the edible nipples. I like "Dogma" and "Jay and Silent Bob Strike Back", but I think they're mostly just good throwaway one-shot entertainment without much resonance or substance (although "Dogma" admirably tries to be more). I think "Chasing Amy" is his best and most mature movie, but I just liked "Clerks" more. They're pretty much equal in terms of quality, but "Clerks" was just funnier.