It was the first automatic Patek movement AFAIK, and I imagine this had a lot to do with the effort put into decorating the rotor (the rest of the movement finishing is great as well). The 2526 was also a very expensive watch when it was released, priced almost as much as a 2499 at the time.
The 27-460 movement that followed had a rotor decorated with a style that is more similar to the rotors of today.
The rotors in the modern-day minute repeaters using the R 27 and its variants have rotors more reminiscent of the one in the 12-600AT.