There's nudity and sex, but that doesn't make this manga hentai any more than the sex in, say, "Last tango in Paris" makes that movie porn. There's quite a difference. Lots of nudity, lots of ecchi and lots of sex... yet it's not porn.
A hint of this is that you won'd find here the most obvious things you find in all hentai. Like, say... genitalia? I don't know you, but to me, no **** (female) and no **** (male) means it's not really porn. Which isn't to say that it isn't very hot... but I digress.
Another hint that this isn't hentai is some reviewers' complains that the girls are slutty (which they are, in a way... though I won't spoil it for you, there are reasons for this). I mean... have you ever heard someone complain that a character in a porn movie isn't monogamous and sleeps around? Yeah... that's my point.
These girls do sleep around with men. They both struggle with their personal issues that go beyond sexuality, and have to do more with self-acceptance, assertiveness, and the ability to trust and love other people (though, as others have mentioned, this isn't an angsty manga). As college students, you could also say that they're in a experimental stage, past their first incursions in sex (common theme to so much hentai) but before having yet figured out their place in life. Eventually, something else developes between them, as they slowly turn to each other for comfort and support (and, huh, pleasure). Sex is just the tool these girls use to relate to each other.
Chapters are all very short, almost like separate vignettes in these two girls' lifes. The whole manga itself is rather short, at only 2 volumes. It did left me wishing for more. It has a somewhat open ending, which might dissappoint some readers, but it's still mostly satisfying.
All in all, a great mix of sweetness, hotness, drama (though not too much), with a somewhat more adult approach than you're probably used to in ecchi manga. I recommend you check it out (if you're old enough to be reading this!) and see if it works for you.