Every other aspect of the design is very well done, although I'm surprised it has such skinny wheels on it. I have a 2011 Z06 with the Z07 performance package that cost me a fortune, so maybe I'm a little biased
Still, that rear fascia looks like something for a Pontiac, it just doesn't flow with the design of the rest of the car IMO. I think it's the tear drop vents on the outside tail lights and the more prominent V shape of the emblem.