Had it done a few months ago. It changed lots of things under PCM/ECU control. I'd just say it drives "different". Mileage is pretty much the same. The two really noticeable drivability items from the reflash are that at highway speeds, it is much quicker to downshift out of 6th instead of building boost and torque to increase speed if throttle is slowly applied; the other is that the transmission has much softer shifts. Not old E4OD mushy, but enough that even my wife noticed the difference when she drove it.
