2010: Most of my thoughts have already been addressed. Honestly I was waiting for more supernatural elements to return, but its turning out that the girl is just a deviant normal and not some mysterious being as I was hoping. The surreal dream sequences in the first volume have faded out, and the series stabilized, with the setting becoming a normal school in Japan (to my chargin.)
One plothole that annoyed me is how the beginning if the main character didn't drink her drool he
would have withdrawal syndromes and sickness, but by chapter 48 he can go a week without her.
Another plothole is in the earlier chapters drinking saliva could show a vivid mental image of the other person, maybe even a memory...but in more recent chapters all it does is give you the feelings of the other person, which are often misinterpretted by the recipitant.
There are some other examples of the author seemingly reversing himself, but I can forgive that since his first one shot was in 2004. I'm just glad the author had the common sense to let time flow in the series (1 year so far), which lets you suspend your belief and accept that the characters could potentially change in that year...not that they change enough....Considering how much the two interact and exchange bodily fluids and share their feelings mentally, you'd think there would at least be able to hug each other by now....The main character, henceforth to be referred to by me as Rei ayanami's cute emo-kawaii syster, is really living up to the title.
One thing that cheapens the series is it's attatchment to fate. Instead of having characters decide they really love each other for their personality quirks, there's a tendency to say "your saliva tastes better;" that physical aspect is as shallow as saying "I keep dating you because I like the color of your hair, or your breasts are bigger than other girls," and it gives up the opportunity for a monologue and the character deciding why he really likes the other person more. The idea of
being bound together by fate is also a cop-out, since it denies the characters the tension from not knowing whether they'll keep their partner or not.
Overall the series is structured like koineko, with a loyal girlfriend devoted and bound to her man. While I enjoy reading it, it has become more of an escapism than the what-if of the surreal beginning, and I hope he just hurries up and has the characters kiss, hug, make-out or do whatever they need to advance to the next stage of development and dramatic tension.
2014 update:
Everything I said stands. The ending was dreadful...absolutely nothing happened despite nearly a hundred chapters. The poor sexually repressed kid stays sexually repressed. I advise against reading this manga past the first volume. Trust me, there is no further plot advancement, and no closure.