Yeah, I have to agree with this one: You need to be a Kevin Smith fan to really enjoy it, because its basically a(n) homage to all of his other movies. Other than that, it's got some funny moments, but nothing to write home about.
If drugs, foul language, overt blasphemy, gutter humor, sex jokes, even more sex jokes, astonishingly phrased sexual references, REALLY overt blasphemy, Matt Damon, and Ben Afflec offend you, you probably not only should not finish watching the movie, but burn the video/DVD.
On the other hand, if you want what amounts to Seinfeld with four letter words and far more entertaining actors, see Clerks--it's worth it.
Then you can wade through the rest of his movies (all of which are slightly intertwined) and watch J&SBSB again--it'll make more sense.
Note: If you think organized religion is a great thing (especially if you're a roman catholic) avoid Dogma. :)