Some time later last year I read (finishing on Saturday 17 October) Paper Towns by John Green. In fact, this may have been the one I read at the same time as Maisie. I thought it was okay; a more traditional US high school novel, but the ending was very anticlimactic.
Much of the book is the quest for the missing, mysterious idealised friend, but when she is found it and she are downbeat and unremarkable, and it just tails off. This would work fine if on the journey through the book you were being given the sense that the journey was more important than the destination, especially in the way the narrator's friendships with the others he involves develop, and in the way the narrator might be developing as a person and outgrowing his need for this rather one-sided relationship - but you weren't. So when you got to the ending you felt 'is that it?', and that you should have been paying more attention to the journey, but not enough was being made of the journey to make you do that - and nor is there even a moment of realisation by anyone in the book at the end that they should have been doing that (which you might have got away with, but I don't think you'd have earned the right to do so).