If you are a devotee of modern American noir, this is probably as close to a "must read" as you are going to get. To summarize in a few words, it is a tough, gritty, even ugly book, that is finely crafted and should prove hard to forget, if at times a little hard to stomach.
First, I am not a student of modern American noir, so I can't necessarily compare Nisbet and his work with other modern practitioners. What stands out for me, however, is this. First, the book is brutally realistic. A great deal of noir, or classic crime fiction, was almost comic in style or attitude. The clipped prose, the exaggerated understatement, the casual violence, the cool narrative tone, often seemed to combine for an almost comic book effect that was not without its own style, irony and humor. We recognized the world it was describing, but we didn't necessarily live in that world--it wasn't entirely real. Not so much here. Nisbet is a good writer. He is terse and to the point, but the effect is anything but cartoonish. The language and structure of the writing is anything but simpleminded, and the small warning voice of fear that whispers on our necks suggests that this is the world we live in: this reality is just around the corner and down the block in a neighborhood we dare not go. No, there is no understated tough guy casually regaling us with tales of "dames" and "gats" (yes, I know I am dating myself), or showing off an almost inhuman obliviousness to or weary acceptance of the dirty realities of a dirty world. Instead, we have a pretty darned realistic main character whose motivations we can actually understand and, to a point, relate to: a failure of an alcoholic doctor with a disaster of a life, and wife, setting out to right a wrong and possibly even redeem some part of himself, but suffering relatively few illusions (even at the beginning, though even these quickly evaporate) that wrongs can be meaningfully righted or lost souls actually redeemed. This type of quest is a staple of this type of fiction; what sets it apart here is the veritable descent into hell that ensues--a hell unexpectedly ruled by a demon queen and not without its own seductive demonic pleasures that undermine any nobility with which the tarnished hero's quest might have begun.
It's also notable that, although the book has its surprises, it is not full of the twists and turns and occasionally ill-concocted suspense of much of the genre. Yes, there is mystery and deception at the heart of the novel that renders the quest quixotic, at best, if not criminally misguided. But the revelation of this underlying deceit flows so naturally from the characters and the situation that, after an initial gasp, the reader could never accept or believe any other reality. "Yes," you say, "That is right. It must have been so." This is no small accomplishment.
My only criticisms, and I have few, are that occasionally the dialogue doesn't quite ring true, if only because a character uses a word or phrase or voices a concept that just doesn't seem natural or explicable by a course in night school (as the characters explain). Perhaps there is a point here: certain concepts, however cerebral, are so endemic to the milieu that the accompanying terminology will percolate even to those depths. Perhaps, but I still found a couple of these instances jarringly distracting.
My only other criticism is personal and, again perhaps, only a reaction to the author's executed intent. The book is extraordinarily dark and bleak. I felt physically dirty at times and found it necessary forcibly to remind myself that the world isn't necessarily like this. Doom, decay and an impulse to erotic oblivion are not its only operative forces. Are they? (Nisbet is good enough that we have to ask ourselves the question. Seriously.) However, I wouldn't for the world suggest that Nisbet failed in any way by not devoting a chapter to "Up With People" or reminding us that the sun will rise tomorrow and the good (at least sometimes) prevail (or even endure). Nisbet set out to show us a perversely seductive descent into a modern hell, and he succeeded admirably. Although I hate such phrases, it would seem remiss not to say that this book is not for the squeamish. Everyone else should enjoy it immensely.