I have previously only had it on rental cars but I absolutely love it. Here in Dallas we joke that you have to get on the highway to go to McDonalds so I use it quite a bit even around town and on some of the back roads here and to me it's about near perfect. I've been quite impressed with it's ability to brake as I've tested it from time to time with my foot hovering nervously over the brake pedal.
Only two strange issues I've seen. First is the following distance as per set driving speed. At Texas highway speeds of around 75mph the closest distance is about perfect, right where I'd normally drive. Keeps folks from cutting in on you. At back country road speeds of 60mph I have to extend the distance setting as it'll be riding the rear of the car in front way too close for my liking.
Second, in eco mode it takes way too long to return to cruising speed after someone in front slows down and then speeds up, often there'll be someone impatient to my right who will take advantage of the new gap so often I have to intervene to get back up to speed or take it out of eco.
I'd been looking at a second gen Sequoia and one of the few complaints about that one was the adaptive cruise control, so I've been happy in that regard with my Expedition purchase.