I really dont think that sexual predators and those degenerates will hand over their phone to the victim to ask if they are "good2go"
Its a nice idea but it just will not work.
This is the reason I dislike this idea so much, because it does nothing to affect the real problem.
People that will actually rape someone, aren't looking for consent, and are not functioning like a normal person, they are looking to exploit weak people.
This app though, the image it portrays is that the normal man doesn't understand where the line is, and can't control himself, so to make sure he can actually 'get with a girl' she has to basically sign a contract saying it is okay... the app is therefore there to protect her from men.
Also, a friend of mine was showed this app by the university he is going to, kinda trying to get the student body to look into it, and use it, and I don't believe such an app should be pushed into the mainstream, it doesn't actually help the rape problem, and it makes talking to people awkward and non-natural.
Men aren't beasts that need to get women to sign contracts to make sure it is okay to have sex, the real predators won't be affected by this.