I don't care if the ending is happy or tragic. All I care about is an appropriate ending. I can't stand when everything changes at the end of the book. I don't like when the solution comes out of the blue without any foreshadowing, or when we find out the whole conflict really was no danger after all.
An inappropriate ending ruins books for me.
I have known where my ending was going to end up since the beginning, but I am wondering how to execute that ending.
It comes down to this question: How bothered would you be as a reader if the book ended on a very public murder, but you as the reader never knew which of the characters was killed?