Despite appearances to the contrary (particularly the OVA, which made me very very nervous), this anime was anything but typical, and even enjoyable. Unless you take it at face value, which I would encourage you not to do. I'm not quite sure why--maybe due to quality banter, timing of gags, use of irony, nontypical reactions/endings to episodes--but the series added up to more than the sum of its individual parts, which, when dissected on their own, seem fairly normal/boring/pandering/weak/bad. But it's a great show, so let me tell you why I like it.
Story: Kodaka, a transfer student, shows up at a private high school, and due to a series of misunderstandings, his classmates are convinced he is a delinquent and avoid talking to him. One day, he accidentally sees a girl in the class talking to her imaginary friend, and she gets the brilliant idea to start a club in order to search for friends. It's a harem show, so more girls assemble and the characters go through a set of stereotypical episodes (beach episode, pool episode, festival episode), while Kodaka (surprise surprise) has flashbacks to a childhood friend whose name he cannot remember. *cue dramatic music*
Characters: The character balance here worked really well. The main character was completely unfazed by the ecchi jokes and naked gags. The two tsundere characters tsun-tsun'd all over each other more than they did over the main character, which was refreshing. The otaku/hikikomori imouto's vampire personality was consistent. The mad scientist never went unrealistically far in her attempts to seduce Kodaka. There was the token "Is he really male?" and forced-to-crossdress character, as well as the 10-year old teacher-who-is-also-a-nun character.
In other words, Kodaka is the only normal human being in the whole show, and the others are clearly portrayed as having become social outcasts because of their own outlandish behavior. What was even more unusual to me is that this set of characters, again probably due to timing and irony, never gagged their gags ad nauseum. (Translation: they didn't annoy the crap out of me like they probably would have in any other show).
Let's Talk about Irony! Actually, the crowning achievement of the whole series is its irony, to which the characters are apparently completely oblivious. That is, by joining a club in order to "practice the skills needed to make friends," they all end up making friends with each other, even though they don't realize it. Awww. To me, that appears to be the lesson in this show: if you're an outcast, grab a few more and have a party! Or an after-school club. It'll be dysfunctional for sure, but then again, you can't spell "dysfunction" without "fun!"