I'll cut to the chase: The Mall is absolutely brilliant.
I had thought that the last word on consumerism came with Fight Club and No Logo, and anything that followed would be a retread of familiar ground, but SL Grey has somehow managed to make this well-trodden theme and everything that goes with it seem fresh again.
I would never have expected this to happen within the narrative of a psychological horror/thriller - I was expecting a simple, lean mash-up of Saw, Cube and Fight Club going by the blurb - so what I read was a nice surprise. Character-wise, I was really turned round on the lead character of Rhoda (an object lesson in how to make an initially unsympathetic person compelling enough to want to be around), and the places that she and other lead Dan are taken emotionally are surprising yet always feel authentic.
What's best about the book is that its premise screams "commercial" but there's more to it than what's on the surface. Part two's bravely luxurious pace allows the character stuff the space to breathe, and while a return to The Mall always seems inevitable (and it's brilliant how it actually seems possible that such a return is desirable), the discoveries that Rhoda and Dan make about each other, and how far both characters have come since the opening of the novel, make their realisation of what they must do have an emotional truth that's pretty rare in today's commercial fiction.
Therefore, what could easily have descended into gratuitous schlock-horror is, in fact, a great character piece. There are still scares galore for horror fans, though, of course. And the narrative is littered with witty, cool stuff. Text messaging from hell. A restaurant called McColons. Shoppers like you've never seen before. There's a bucketload of imagination on display here and I loved reading it.
So my advice is to buy The Mall - right now if you're lucky enough to own a Kindle, but definitely when the book is released in hardback later this year. As others have already said, you'll never look at a shop mannequin in the same way again. More importantly, though, after reading this book you'll be counting the days until SL Grey releases his/her next novel.