I would rather not have it because I hear it can make the car harder to control once you lose the rear end. Besides, like someone has mentioned, just about every car that had rear active steering(FC RX-7, 240SX, 300ZX, etc), has a kit to eliminate it.

 

pros-
easier to drive the car faster

cons-
price
weight
may hinder raw performance


having said that- for a vast majority of drivers, the system is beneficial