Here's the thing for me.
1. I really don't like Ares as a mentor and would much rather have seen Athena as a mentor as it makes a lot more sense considering Diana's origins.
2. I love the way Ares is being written in the book and the interplay between him and Diana, but I still would have preferred Ares as a villain.
It just feels 'what if Lex Luthor had been Clark Kent's science professor and mentor in high school' and the entire 'villainy' angle of the character removed. Ares has been her antithesis from the get-go and I miss that.