I almost didn't finish Nightfall.  The first part of the book, the part shown off in the free Kindle sample enticed me.  It wasn't much further in, however, that the book started to drag for a bit.  There's a lot of establishment early on which slows things down, but I don't think I would have enjoyed the end if Leather hadn't established the world and people around Jack Nightingale so thoroughly.  By the last third of the book, I didn't want to put it down.