My thoughts: If you ask anyone, what a good crime novel is all about, they say it's a book that keep you guessing. There are different ways of keeping a howdunit / whydunit like this one mysterious, and Higashino somehow doesn't get them - in neither his previous book The Devotion of Suspect X, which was quite a phenomenon nor Salvation of a Saint. We already know who did the crime and as the book progresses we watch the police and detectives try to figure it out, trying ourselves to figure how Ayane committed the murder and why. The investigation goes around in loops; junior detective Utsumi suspects Ayane, but couldn't tell you why and Kusanagi, our hero, seems to have fallen for the beautiful widow. For the first hundred pages of the book, it is impossible to guess just what might have happened - the reason being, nothing new really comes up - the same conversations with the same few suspects, minutely detailed descriptions of feelings and analyses and different perspectives on the same thing. The investigation becomes a drag (although I rather believe real-life investigations would be just as repetitive and unlike the fast-paced action most books provide.) The detectives' constant state of being confused forms a major part of the book. And just when, somewhere in the middle, the writer lets slip the first obvious clue of why the crime could have happened, figuring out the whole reason is a piece of cake. Infinitely easy. So, I could guess the whydunit there and then and that part of the mystery was lost. Then came the howdunit. You know the man was poisoned, you know, from the prologue, that a bag of white powder was somehow involved in the crime. You couldn't possibly figure out the method used to poison, but when you know who and why, does 'how' really matter? Enough to read half a book? If it does, well, let me tell you, I could vaguely guess what must have happened forty pages before it was revealed, or could at least guess the components involved in arranging that crime (let's put it that way, if we want to avoid spoilers.) And when I did find out the whole truth it wasn't as ingenious as I would have liked it to be - in fact, it was kind of ludicrous (and also kind of moot, which you'd understand if you've read the book; tragic how Ayane went through so much only to be caught.)
If a good crime novel really is one that keeps you guessing, this isn't it. But I think people put too much weight on suspense. For me, a good book is so much more than "What happened? What happened? What happened? Oh! THAT happened! Wow."
The book deals with many social issues; you almost relate to the killer, which is saying something. There is no definite bad guy, just a string of unfortunate situations and behaviour that spiraled off to a murder. It makes you wonder how sordid the world has become, how biased and superficial our actions and emotions are, how helpless we often feel and how blurred the line between right and wrong is. The motive for the murder is just typical enough to be believable, the characters are really fleshed out. Ironically, I could connect to them better, because they were almost irreparably selfish and flawed.
(By the way, good work by the translator as well, the words flow in a way that makes it hard to believe it's a translation - as I remember, The Devotion of Suspect X was a bit clumsy: which is odd, considering it's the same translator.)
Like I said, if you're looking for a fact-paced thriller, surprising, crime mystery novel thing, this is probably not it. You would probably enjoy The Devotion of Suspect X a lot more. But if you want a good book, one that lingers on your mind long after you've finished reading it, I would suggest you go ahead and read this one. I certainly liked the book.