I've got the new Hyundai Ioniq with adaptive cruise control and lane assist. Last weekend I drove 160 miles with both enabled for the first time. I just found it shifted my focus. I was much more aware of what was going on outside the car. Setting the max speed to 75 mph enabled it to follow the car in front very effectively and overcame the incline and corner speed issue. Only problem was having to intervene to prevent under-taking.
I second the effectiveness and pleasantness of Hyundai's implementation. My 2015 Sonata has those features (its standard now, but was introduced that year for the Limited trim). It, combined with auto-hold to apply the brakes when the car stops, made road trips and slow going commutes so much more pleasant. It sucks for stop and go traffic, since it disengages when the car completely stops. But I can't fault a cruise control system for sucking at a scenario that doesn't actually involve cruising.
