Wonder Woman's mythos presents many problems, but the basic hook to the character, particularly in her first appearance, is really not that hard. Diana's a newcomer, who has long dreamed of exploring the wider world, which she's been sent to save. She believes in peace, justice, all that stuff -- not really that different from other superheroes.
If a lesser known Thor can succeed as a movie with his epic fantasy background, so can a more well known Wonder Woman.
I think that is exactly the problem with Wonder Woman. People like the general idea of a female protagonist superhero called Wonder Woman, but really they are pretty cold to the actual Wonder Woman character itself.
And there is a lot of stuff there that people don't like that is part of her character, which you can't toss out.