I was expecting a bitter-sweet ending, and I have to say this was even sweeter that I thougt ^^
At least the series has shown the guts to deal with reality, even when it's hard to face. I prefere a sad but close to reality storytelling, than an happy miracolous one.
Nice ending, I agree with "the kiss was natural". While for the sensation of rushing things off, I've seen much worse rush-off than this one, which hence I consider good
Great characters, even Natsume despite his hard surface had an important role for the show. I was guessing this even earlier, though the hints seemed to bring him as a love opponent for Yuuichi. This doesn't mean I forgive his behaviour, but there so many scars in his past (for his fault, but also not) that I think that at least in a minimum percentage is possible to sympathize with him.
The series then, shone also for musics (heartwarming Ending Theme, and wonderful OP too), and voice acting: Takahashi Mikako was great for Rika, as well as Kenichi Suzumura for Yuuichi. Also the nurse was excellent, while Natsume's voice was fitting the character very well.
Overall a little gem of a series. Really. Original setting and original narration. 2006 is being generous of good shows, so far.
As always, I put my overall rate when commenting a finished series, and for Hantsuki it is a
9.3/10 (animation:8 - sound: 10 - story: 9 - characters: 9 - value: 10 - enjoyment: 10).