In a post on Whedonesque the writer and director says:
You (hopefully) heard it here first: I’m no longer slated to make Wonder Woman. What? But how? My chest… so tight! Okay, stay calm and I’ll explain as best I can. It’s pretty complicated, so bear with me. I had a take on the film that, well, nobody liked. Hey, not that complicated.
Let me stress first that everybody at the studio and Silver Pictures were cool and professional. We just saw different movies, and at the price range this kind of movie hangs in, that’s never gonna work. Non-sympatico. It happens all the time. I don’t think any of us expected it to this time, but it did. Everybody knows how long I was taking, what a struggle that script was, and though I felt good about what I was coming up with, it was never gonna be a simple slam-dunk. I like to think it rolled around the rim a little bit, but others may have differing views.
The worst thing that can happen in this scenario is that the studio just keeps hammering out changes and the writer falls into a horrible limbo of development. These guys had the clarity and grace to skip that part. So I’m a free man.
It would appear to be an amicable parting of ways but its sad that someone as smart as Mr Whedon is no longer involved with the project.