I have only read two volumes, but felt SOMEOME should write a review!

This is an interesting manga, the strength to me is the insights into everyday Japanese life. There is an index at the end of the book explaining different words, puns and concepts familiar to Japanese readers, but you would have to be a scholar to know them if you are American.
One downside for me is I am constantly flipping to the end to read the references - which breaks the reading flow and makes the read a lot longer than it should be. The manga almost demands two reads, just to get through the story unbroken once.

The characters are all over the top - taking one particular aspect and carrying it to an extreme: the eternal optimist, the control freak, the suicidal depressed teacher, etc.

Each volume consists of a series of chapters, pretty much unrelated, that deal with a character's personality, and the explanation of why a trait is ridiculous or useless in society. The teacher in the series is always pessimistic, but it ends up somehow improving his students. The students ALL have some issue, and the class is a collection of misfits that the school administration marvels at - because the teacher seems to have such a rapport with his class.

Not sure how long term of a read this is - it seems a little open-ended to me right now - like a series of sketch sitcoms.

Overall, a fun read, with lots of cultural references. Worth a look.