I discovered Patrick Ness' A Monster Calls via one of Niall Harrison's tweets. I'm sure I glad I did (thanks Niall!). I don't read a ton of YA, but this book didn't in any way feel restricted because of its target readership. In fact, the fact that it was YA may have strengthened the narrative, making it taut and focused whereas in an "adult" novel it may have contained digressions or other non-essential material. I guess YA readers have figured out this sort of thing decades ago. I'm a slow learner.
In any case, I have to say it blew me away. Despite all the favorable attention Ness received for his previous works, I'm new to his writing -- but I won't be forgetting his name any time soon. I think the less said about the actual content of the book the better. Niall's brief description sums it up well.