I have zero literary expertise, so on that level I can only defer to the Man Booker Prize committee who thought highly enough of this novel to rank it as a finalist. I would imagine, though, when it comes to how your book-buying public reacts to your writing, the ultimate achievement would be for readers to say, "I could not put it down." To Sarah Waters: Mission accomplished.
I received this book from my sister Saturday afternoon, began reading Saturday evening, very reluctantly went to sleep at 1:00am, up at 8:00am, and finished the book without leaving my bed. "I could not put it down" is often not meant literally, but not in this case. I could not put the darn thing down. I am not sure that I can even clearly explain why.
As far as being 'un-put-down-able', the first reason you might expect would be that it's terribly suspenseful, keeping you on the edge of your seat waiting for the next horror to occur. But, really, it wasn't that at all. I mean certainly, it is a bit suspenseful, but it goes on for about 100 pages before much of anything really happens. ( Don't misunderstand, even in those first 100 pages you could not have wrestled the book out of my hands).
I might attribute the interest to the subject matter, a decaying stately English home and the decaying gentry class, which is certainly interesting, but not exactly page-turner material. It could be the characters that are so compelling, but no, it's not really them either. At least at the outset, everyone seems rather normal with the expected burdens of their life's lot. The writing style itself befits the subject matter, but it wasn't the kind of prose that made me think, "Oh, this writing is so beautiful (or clever or what have you)."
I can only conclude that the success of the book is in the combination of setting, subject matter, characters and writing style which, while none particularly stood out on its own, as a sum total worked incredibly well. It completely and utterly draws you in to its world.
I won't go into the story detail, no spoilers here, but it's a historical, curious and melancholy gothic mystery.
And it doesn't like to be set to rest until finished!