First things first: I read this whole manga in 1 day which could be reason enough for some, to read it too
Second: I never wrote a review before, but i just can't keep quiet about this

As for the ratings:
Story: 9
If I had to describe the story of Bitter Virgin in only one sentence, I'd just say "It's something else". If you're bored by the everyday shoujo manga, with they all-is-well school days atmosphere, then you're right here. I don't want to reveal too much, as you should read it yourself, but this is about a "dark" side of the not so everyday life, which i don't remember to be shown anywhere else (neither manga nor anime)

Art: 7

Not too bad, but nothing special either so a "good" should be ok for it

Character: 9

The tragic protagonist Hinako, together with the also tragic sister, which rises from the support to a main character (in my eyes) are the core of this drama and u can easily get lost in their despair and struggling. they both get support from Daisuke, who undergoes a change for the better with time passing by.

Spoiler, so be warned about the next lines
The only reason, why I don't give the full 10 points here, is cause of the typical, as I phrase for myself, bitching-around-attitude in the end (meaning the "Oh no, I better go away and leave for good, cause else I might hurt the one i love")
Spoiler end

Enjoyment: 10

Well...I read it in one day, so i don't have to say more about enjoyment

Overall: 9

If someone asked me for a manga he could read next, Bitter Virgin would definitely be a suggestion :D