Though I did not like the book, I can't deny it is well written with a great deal of mystery and suspens, and a lot of cynical humor, in all fairness and objectivity, so I can understand why some people like it. But not everyone will, I guess it depends on your sensitivity.
Subjectively, I found it very offensive socially and I could not get to like any of the characters. They all seem caricaturally misandrist and sometimes racist visions of men : unfaithful, machist, egocentric, abusive towards women, even the "good" guys, violent, money & ambition driven, alcoholic etc. And the female characters are very shallow (girlfriends or the girls of one night basically who have absolutely no power nor mind except one excentric old lady towards the end).
But I read 'til the very end, all 600 pages, just to understand and was therefore very disappointed, as many other readers pointed out, there is NO explanation in the end. It makes no sense at all... but I guess if you don't mind despicable characters, if you are a bit cynical, it may be quite a funny book and an enjoyable read.