Spoiler Alert: If you have any plans to read 1Q84, do not read further. Come back when you've read the book.
The thing is so massive that this is going to a collection of random thoughts.
1) The basic story is simple. Two Japanese 10-year-olds, after a silent communication in elementary school, fall in love and twenty years later manage, after many complications meet to consummate the love they've maintained through all the years.
2) The young woman, Aomame, murders abusive husbands in a way that is undetectable after a cursory postmortem. She shows no guilt, remorse, or qualms about the murders. She seems, in that sense, to be perfectly amoral.
3) The young man, Tengo, is an aspiring novelist. He's big and strong and women find him attractive, but he seems to be almost indifferent to them (except for their breasts). He has a married lover, ten years his senior, who visits him periodically for her—and his—sexual release. Midway through the novel, the lover's husband calls Tengo to tell him the lover won't be coming around any more. Tengo takes the news in stride, makes no effort to learn more, and we never discover what happened or how the husband learned of the affair.
4) In the first chapter, Aomame, on her way to murder an abusive husband, walks down an emergency exit from a Tokyo expressway and finds she is in an alternate world, one in which the Japanese police carry weapons, there are two moons, and there's a joint Soviet/US effort to build a base on the moon. In this world, it is no longer 1984 but 1Q84. After some half-hearted efforts to learn more, Aomame accepts the new world and continues her life much as before.
5) A policewoman friend Aomame makes is murdered during rough sex in a Tokyo hotel. The murderer is never found.
6) Tengo has intercourse with a 17-year-old girl, Fuka-Eri. She is not worried about getting pregnant; she has not started menstruation. Aomame, on the other side of Tokyo and who, at this point, has not reconnected with Tengo does become pregnant. Aomame, although she has not seen or heard from Tengo for 20 years and has not had sex with anyone in the period in which she became pregnant, realizes she is carrying his child.
7) Virtually all of the cultural references are western: music (Leos Janacek, Miles Davis), movies ("Thomas Crown Affair,"), books (Aomame holed up after murdering the leader of a religious group, reads "In Search of Lost Time"). All of the action takes place in Japan, in Tokyo and elsewhere.
8) The book left me with too many unanswered questions. I'm willing to accept a world in which a man can have sex with one woman and another—his true love—becomes pregnant. I can accept a world in which Little People come out of a dead goat's mouth and build an Air Chrysalis. But I want to know what happened to the married lover. I want to know what happened to Fuka-Eri, who is a major character but who simply walks off stage and disappears. I want to know more about the religious sect, a key institution in the book, their beliefs and why a best-selling novel is such a threat to them.
9) I think the book needs an editor. Although how do you tell an author who reportedly sells a million copies of the book in the first few weeks it's published in Japan he needs editing? But people continually echo what someone has just said. They muse interminably about unanswered and unanswerable questions. They ask rhetorical questions. They think in long italic sections.
10) Finally, having slogged through all 925 pages, I'd like to have something for the effort. This may well be my failure, my inability to see themes or to read into the text the deeper meanings Murakami has imbedded. Is it a good idea to murder abusive men that the law can't touch? Are there alternative realities we can slip into like a train switched onto another track? Is the emotion you felt as a 10-year-old strong enough to sustain without any contact for 20 years? (I had a lot of trouble with that idea, but I'm probably in a minority.) Can a novelist create an alternate reality in which other people can enter and live?
Maybe that's what Murakami is doing.