What exactly is a Mustang supposed to look like?
I like both of them and if I really felt like arguing about it I would say that from the side the 2015 "looks more like a Mustang" based on the roof line sloping to the trunk and the flatter shape of the hood. But in reality, I don't think either one looks more or less "like a Mustang" than the other.
I think a lot of these posts are just ways for posters to justify to themselves or others why they like one car or the other. I like both of them and don't really care which looks more or less "like a Mustang". There were 30 years in between that looked a lot different than anything before and after.