I still have a very neutral opinion of the new production design. While I feel the new interior is a major improvement, I don't like the plainness of the front, the bubble hood, the fog lights, the rear side window, the exhaust, and the bottom of the rear. Like someone already mentioned, I wish I wouldn't have seen the concept, because the final version looks very cheapened.
The front of the concept was such a great design. It had retro styling, but it looked so futuristic at the same time. What we're left with is a design that seems 5 years stale. What I mean is that if you pulled aside a sheltered person, set up an 80's mustang and a 1994 model, they could easily tell you which was newer. If you set up a 1994 and 1999 mustang, the newer model still jumps out. Now if you set up a 1999 and 2005 GT, I think this person would be torn as to which is newer.
I guess this is good for me, as I don't feel as if my current model mustang looks outdated now. And as for the comparison pictures above, nice, but you truly need the same angle and scale to be fair. If the picture of the current model is angled more toward the front, it looks much more muscular.
I would still buy the new model, but it's not a "WOW---I have to own that car" feeling. Eh, it's okay.