Today Comic Book Therapy translated a french article from Popcorn Magazine that spoke with Zack Snyder at a 300: Rise of an Empire promotion event. It eventually came to Batman vs Superman which he spoke about the casting of Ben Affleck:
"Ben brings an interesting counterweight to the performance of Henry [Cavill's] Superman. [Affleck] has the experience necessary to paint the picture of an older and more [advanced] man than Clark Kent, [one] who bears the scars of a seasoned vigilante while [simultaneously] retaining the charm that Bruce Wayne deploys when present in the world."He also adds that Frank Millers The Dark Knight Returns will influence his take on Batman but won't be a direct adaption.
Batman vs Superman hits Summer 2016