Haha, yeah, I went pretty crazy over Punpun some years ago, a comic I had drew some influence from it (but that comic is long gone).
Yes, it's not a comic for everyone, I guess you either love it or hate it. Filled with sexual frustration and depression, aside from infidelity, child abuse, suicide, murder... You're really in for a ride if you decide to pick it up.
But certanly a work like Punpun has cemented master Asano Inio as one of the leading mangakas of the new generation. Currently reading Dead Demons, let's see how that one keeps unraveling. Like sachi says "I'm going to crush the world with my manga".