*SPOLER ALERT* There are minor spoilers in this review.
Oyasumi Punpun is a strange way of looking at a slice of life. The story (so far) follows Punpun Punyama from an elementary schooler with a weird attraction to a bullying girl through to a university student Punpun making sense of love and betrayal, all portrayed through the eyes of someone who looks like a bird. At its heart I'd say it's a manga about a child growing up with divorced parents and the issue of identity, as Punpun looks more like a person as the manga progresses. But then I'd say it's none of those things, it's just a comedic slice of life about a quiet person called Punpun.
Story - The story is your typical slice of life but on a much grander scale as you get to witness Punpun growing up, his longstanding love for the girl he knew as a child (not the bully), coming to terms with his parent's separation, understanding his depressed uncle and finding out how his childhood friends grew up. It starts off heavy with comedy but as the story progresses it becomes more serious whilst still keeping its utter craziness.
Art - The art is terrific, it starts off perfectly with Punpun as a hilarious small bird with no arms that stands on his seat rather than sits and is at least a foot smaller than everyone else, the fact that Inio Asano can make a bird fit in so perfectly when surrounded by people is quite something. The reason I have given it a meager 6.5 is because as the story progresses, the laziness of how Punpun is drawn increases, first the frills go, then the form, until he's just a misshapen rounded rectangle with hands and legs. You might argue this shows his development and how he's losing his identity because he wears brands and becomes just another Hollister Hipster rather than Punpun as an individual, but it was still disappointing to lose part of what made the manga so funny.
Characters - The characters are very unique, from Punpun's love Aiko, a complicated daughter of a cult religious organisation to Punpun's uncle, a depressed middle aged bird who steps in to help his sister (Punpun's mother) look after her child. Almost everyone has a scarred past, even the minor characters, which may be a shout out to modern anime and manga where the main character always has a hidden past or it may just be the author's way of making the manga more interesting.
Overall - Read it when you're in the mood for a surreal slice of life but don't read it because you enjoyed Yotsuba&! because they are completely different slices of life. The manga will keep you reading but you have to be in the mood which is why I've given it an 8 overall.