Never did like the '05-'09 style. I really tried, but they just seemed too....plain to me. Even the back end never turned me on.
I liked the '10-'14 almost immediately. The rear end took some getting used to...but I still like them better than the previous generation.
The '15+....well, I guess we'll just have to see what they're like in person. SO far, I'm digging the lines. A little bit too "European" looking at some angles for my taste, but that's progress I suppose?
I still think the SN95 '03-'04 Cobra was the nicest looking Mustang produced in the last 35-years though.