Hate adaptive cruise control - when someone cuts in front of you the car lurches as it suddenly slows down, sometimes enough to wake you up. Far easier to stay in the outside lane with the foot down, only pulling over for BMWs, Audis, Police cars and Bedford Astramax vans.
Automatic braking occasionally gets it wrong, it thinks you're about to clip something, the entire dashboard turns red and the brakes slam on. Got a fair fleg the first time and never really trusted that car afterwards.
Automatic headlights are good, except my current car doesn't have them so I just drive around with the headlights on all the time so I don't forget.
Lane departure systems are amusing for all of 15 minutes, then you switch them off.
Similarly, who actually has the volume up on their sat navs? Nothing more irritating.