I've owned a GT, Spur and now the GTC and this is the best of all three. Better drive/ride/handling than the GT and Spur - AND, as of 2008 model, they've eliminated all the kinks/idiosyncs out of the electronics, esp. the phone and nav. system from the earlier models. The GTC is a joy to drive and a head turner. Build quality is better than ever and the sound system, in a word, spectacular. The GTC is, in a word, masterful. Even the Breitling clock is improved!
Handling. Styling, both interior and exterior. Sat Radio (now standard for life). Massive power and smooth as silk drivetrain. Though top isn't metal - it is amazing -- and interior sound level is amazing for a convertible. No wind noise.
Wish they had "Onstar"/"Teleaid" assist button (got used to them on the ole Benz's --and another 6" in backseat legroom! (but hey- it's a convertible). They got rid of the free maintenance though a BIG bummer!