I love the new body style! I knew as soon as I saw the new body style before they even were in production I had to have one. I have owned a '79 and '81 Mustang, they do not even compare to my '05. I have had some minor issues such as CD player replacement and driver's side door handle problems but those were taken care of pronto. I do not plan to get rid of this car. I am very happy with my purchase.
Body style of course! You have so many options, you can really make it your own.
More padding in the seats (leather). Better fuel mileage (but everyone is looking for that aren't they?).