Rebecca Ferguson may be best known for her role in the Mission Impossible franchise as Elsa Faust, an asskicking British special agent. She has been in the last two films as a major character. In fact, it's not common for characters in that franchise to return, other than a few key people, so it goes to show just how important and popular her character was in the series. She proved her penchant for playing sexy yet deadly, which might be a great way to describe Wonder Woman.
Being an English actress, she may not be exactly right for the role. That's especially true when you consider the exotic aspect. Her accent would be bizarre on Themyscira, so she would have had to adjust that. Luckily we will most likely see more of her in the future Mission Impossible movies.