ART: The art is very appealing, and it uses veeeery exaggerated expressions to convey thoughts, which does help the humourous aspects of the series.
PLOT: What plot? The plot of this manga is not very... corporeal. It kinda sits in the background, twiddling its thumbs behind the curtain. The only plot is not a huge focus, since this is supposed to be a humourous, random manga, not an angst-ridden, serious series. And yes, there are many issues involving common sense, but there's a little something called "suspension of disbelief" that is necessary to enjoy the series (or any series, for that matter). So these issues didn't really impact me at all. As for the ending, yes, it was a bit lackluster. But, then again, the series itself would've been difficult to end on any note, and it makes sense that the author would want to choose an open ending over one that is more concrete.
CHARACTERS: They are varied and absolutely hilarious but still believable. No one is "perfect," which is a bit plus.
In short: if you want a manga series that's light-hearted, hilarious, and a bit perverted that doesn't put much focus on plot, then this is a perfect choice. But if you're into the more serious spectrum of manga, skip over this one. Also, if little inconsistencies (or breaks in logic) annoy you, you'd best stay away, since this is only for humour.
Why did I give it a ten despite its issues? Because it fits its genre perfectly and did what it was supposed to do. It wasn't weighed down with useless information that would be necessary to fill plot-holes or angst-ridden flashbacks/occurrences. As the subject says, this is a great manga if you're looking for something of this particular genre.