Wonder Woman was the first time I've seen a female superhero get the same treatment guys do when becoming superheroes. She began the film naive, witnessed unspeakably awful human behavior, and rose to fight it.
Women are celebrating this movie because it's a female lead, a female director, and one of the incredibly few superheroes ever put on the same level as a Superman or Batman--male or female.
I'm nowhere near a SJW or anything like that. I think this movie is a significant groundbreaker for women though. Also, I read that the audience was 53% female, so there's a market to be tapped there that has long felt ignored.