As a Ford guy I've always liked the Mustangs. OK I take that back.. I never was a big fan of the Fox body (80's) but oh well. When they redesigned it in '94 I thought it looked cool but I quickly leaned that everything was just... cheap. The new '05 design was a HUGE leap in the right direction. A lot of the quality returned, it looked neat, and it went from feeling like a "cheap" ride to feeling like a "luxurious, quality" ride. Everything felt heavier and more solid, and the entire car was more stable as a result.
The problem is that they haven't really made any big changes since then. It's been seven years now and while GM and Chrysler have released their competition by 'bringing back' lost models (Camaro and Challenger), Ford really has nothing to offer someone looking for something new and different as far as sports cars go. In order to stand out, Ford has to continue to change and evolve the Mustang *BUT* to be fair that costs money. Since Ford declined financial assistance I'd imagine that their R&D funds were quite a bit lower... while GM and Chrysler were sinking millions into their sports cars to try to make a quick buck, Ford was busy restructuring their ways of doing business for long term success.
At least that's my theory.
Personally I'm not worried. Even if they end up eliminating the Mustang model altogether like Chevy did the Camaro - in a few years they'll come out with a whole new car that will just BLOW AWAY the competition. Maybe by then I'll be in a financial position to actually OWN ONE! haha