I’ve had it in 2 cars (still have it in 1) and if the implementation is good (ie if it is seamless with smooth shut downs and re-starts, if the hardware upgrades like battery and starter are properly done etc), I think it’s a good feature and I have gotten used to sitting at stop lights in silence and peace (except for my music of course). Once I got used to how it works, I find it relaxing and appreciate every minute of lower emissions. I’m less concerned about my gas mileage - except maybe with this thirsty G70 .
On a side lighter note it also leaves 2 blank buttons in the centre console for the camera and the stop/start switch and those blanks make me sad. ;-)