Just read some of the comments on that forum, and I think anyone who calls the Camaro's interior ugly while claiming to like the Mustang's flat, boring interior looks great needs to drop the crack pipe.
I have two good friends with newer Mustang (05 and 06), and the interiors look pathetic. The side edges of the dashboard (where it meets the doors) don't even line up properly. It doesn't look professionally designed at all. The center console is yawn-inducing, and the fake "chrome" trim looks like ass. What were they thinking? Even the steering wheel looks lame. Whoever though the flat grainy plastic look was popular needed to take another poll. Even the square, blocky rear-view mirror lacks any sort of style.
I always try to be somewhat positive when talking about something, so I will say that the seats are pretty comfy.