Mine's got it - sometimes I've noticed it kick in. But at the times I've expected (and wanted) it to kick in, it hasn't. Therefore I can't adjust my driving style to safely rely on it ! Just like the the start & stop, it has a mind of it's own.
Someone else on the forum said start & stop is like driving with a toddler that keeps snatching the ignition key away. Maybe this is its brother that keeps tugging at the handbrake!
I kind of wish they hadn't bothered fitting either system....