There may be a good novel struggling to get out of The Amnesiac. If so, Sam Taylor has been let down by his agent and/or editor. Because this book is in serious need of pruning, both in terms of style and content. Stylistically, there's a huge amount of redundancy and repetition. Things are eternally happening "suddenly", "for some reason", "for the briefest of moments". Everything is prefaced with "James thought" when it's perfectly clear who's doing the thinking. Taylor also overdoes it with the adverbs. He can never say that someone simply says something. They have to say it menacingly, slowly, softly etc.: '"I'm not sure," he said cautiously.' Yes, we KNOW he's being cautious if he's refusing to say yes or no! Leave some room for the reader's imagination! Taylor would do well to google Elmore Leonard's Ten Rules of Writing...
Unfortunately, hitting the reader over the head is Taylor's style. Every few pages we're reminded that the protagonist James Purdew (Purdew = perdu = lost, DO YOU SEE???) is in a labyrinth and that memory is chimerical. Yes, we get the point! The influences on this novel seem equally brute, undigested. You go through the novel thinking, yes, this bit comes from Auster (Daniel Quinn, an Auster protagonist, is actually 'thanked' in the acknowledgements), this bit from Bardin's Deadly Percheron, this piece of nonsense from Fowles's Magus, that plot device from The Eternal Sunshine Of The Spotless Mind, etc. etc.
At the same time, the novel lacks narrative focus. Thrillers need a tight focus, and yet pages and pages of extraneous stuff - about the protagonist's teenage girlfriends, about his time working on a newspaper, etc., etc. - could have been profitably removed. It also lacks a central conflict of personalities. There is really only one person in this novel.
All that said, there are nonetheless some interesting ideas in the novel, and I hope that Taylor goes back and sees where he got it wrong, and comes up with something a little more considered for his next effort.