Genshiken is funny. The End.
Seriously, though, this is usually the only thing in comedies that matters. In anime like Dragon Half, Golden Boy or Fumoffu, there really isn't any point other than the sheer quality of the gags. Watching any of those series for anything but laughs is about as productive as using a condom as a water balloon. Sure, you might be able to do it, but you're missing the point entirely.
This isn't really the case, however, with Genshiken. Even though the show is a comedy, the creators are sure to also include some fairly interesting insight into true otaku culture (not the wannabe stuff found in the US). The look into what actually makes these dysfunctional folk function is so intimate, honest and perceptive that only an insider could have ever made it.
None of the otaku in the show are really developed fully as individuals, but as a group they become a living, breathing, and believable portrait of what has become Japan's most defining subculture. In the end, the collective actions are filled with flavor and are the true heart of the show.
Saki, the other major character in the show, acts as a tool to draw out the inherent humor in this brutal honesty. The simple juxtaposition of a relatively mainstream and normal character with the rest of the cast is all that is needed to allow for a good deal of the humor.
When the jokes are handed out, the style is decidedly unique from most comedies that I've seen; whereas most non-ecchi gag series merely try to be as wacky as they can be (FLCL, Hare and Guu, Excel Saga), Genshiken relies primarily on understatement and subtlety. Many of the funniest parts are in the long silences following something extremely awkward, and there are numerous running undercurrents of humor that are never explicated to the point of eliciting a laugh. Some might take issue with this style, but the approach was more than satisfactory for me.
After all is said and done, this is a surprisingly intelligent comedy that manages to be both interesting and likeable. Oh yeah, and Genshiken is funny. The End.