Saw the tree today and it's brilliant, the nooks look really cosy and every one was occupied! In fact there was a really nice atmosphere around there. Some of the "books" are actually lights, and it's narrower than it looks in the photo,I love the staircases as well.
I did go into Hatchards as well, but they didn't have the book I was looking for. Nice shop though, with some lovely book-themed tote bags.