Hideo kojima the Creator of metal gear solid was in a similar position with the fourth one. He was tired of the series (he spent at least 13 straight years working on it) and wanted to move on to something else. In the end; the game felt under the standards of its own series. However, the ending was Worth it, he actually gave resolutions to everyone and did not spit on the message of his series. Raiden (the player who hated and did not understand the beautiful message of 2) backtracked on his character development but in the end the protagonist (kojima) still managed to make him understand what the author was trying to each. Kojima was tired but never conceded defeat on what the series was mainly about (the message of 2 of being your own man and choosing your own life) until the very end.
^^ Thanks for the excellent example of a creator not kittening on his artform. The message, its all about the message. And the mangaka failed himself and his characters.