I bought the last two volumes as an appreciation for Koga-sensei coming to Fanime 2006. I even had my first two volumes autographed there. He drew small funny-looking Onsokumaru on both.
However, it still doesn't change my mind about the books. It's not all that funny because it's mostly forced funny. I mean, you look at a funny scene in Yotsuba&!, it doesn't need any explanation. Laughter just flows out from deep inside you. You look at a funny scene in Joshikousei, Girl's High, it's just outrageous. In contrast, I can't tell where this story is going.