Cromartie Koukou is a high-school in Tokyo with loose entrance requirements. How loose? A gorilla (an actual simian primate) and a middle aged man (that resembles a certain deceased rock-star) are students there. Not even the worst students mind you; Cromartie has a collection of the dumbest and most hardcore delinquents in all of Tokyo.
A good premise for a gag manga, but where is the straight guy? Enter Kamiyama, a painfully mainstream character that makes the dubious choice to attend Cromartie. The mangaka, Eiji Nonaka, has created a good setting and takes advantage of both his premise and
his inspired drawing, to deliver the comedy.
Cromartie students try to further cement their school's status as the most badass, gorillas keep filling the classrooms, aliens invade, and no one knows where the teachers are. Amidst all this chaos, Kamiyama approaches each situation with a cool head and tries to set his fellow classmates in order.
If you are into comedy you are going to laugh hard, and if you are into absurd comedy you are going to love it. I always looked forward for the last page of the chapter for the mangaka to deliver the punchline along with some excellently drawn reactions.
It's all fun and laughter for the first chapters, but after a while the humor's quality and the number of laughs decreases. When the number of chapters reach triple digits, the quality has reached a low level and for the next 100+ chapters the manga is just running of fumes, delivering a single dry chuckle every few chapters.
My suggestion is to start reading the manga, but whenever you enter a 10-chapter dry spell, just drop it. It is not going to pick up the pace for you ever again. If I had dropped it at around chapter 110 I would have given it an 8. I persevered until chapter 223, so 6.0/10.