I have a Subaru with lane-following and adaptive cruise. Lane follow fails miserably because it keeps losing the lane boundaries, even on clearly marked roads. But adaptive cruise control works extremely well, and particularly shines in stop-and-go traffic.

One catch there is that it'll stop automatically, but it won't ever go if it came to a full stop - you need to tap the gas to reactivate cruise. If the car in front of you starts moving, but you don't move, it'll make a noise (both audio, and visual on the dashboard) to remind you that you're supposed to do that. I suppose that's a kind of a safeguard to keep the human alert?

I also drive a new-ish Subaru, adaptive cruise seems to work well in some situations (low speed stop-and-go, like you mentioned) but at high speeds it is terrifying... A speed that is reasonable on straight highways is pretty jarring around curves. If my foot is on the gas I'll subconsciously make the needed adjustment, but with cruise on I don't usually react in time.

This could partly be a consequence of living in the Pacific Northwest... lots of winding mountain highways!

I'm in PNW as well. I find that it works great on major freeways - e.g. I commute over I-90, and it works great there. On I-405 as well. On the mountain routes, like say parts of SR-202, yeah, it's ill advised.

On most highways you can maintain speed through curves, but not in the mountains, and they do warn with plenty of signs. So CC is not a good fit for mountain driving.

That sounds at least somewhat workable. The Accord seemed to drop out of cruise control if the speed dropped below 15-20 Mph, so it was entirely useless in stop-and-go, and even slow-and-go.

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.

The 2018 model year (I believe) has full stop-and-go support. The previous two model years would cut out somewhere around 25 mph (this is what I have). It really is only for freeway driving outside of heavy traffic. I've used a 2018 CRV that has stop-and-go support and it's quite nice.

The lane tracking isn't that great, but I don't mind it that much. I don't use it much for normal driving, but I found it it's pretty fantastic in heavy crosswinds. The car does a pretty good job of keeping the lanes (assuming you can see them well enough) so you basically drive like normal instead of having to constantly fight wind gusts.

Under normal conditions it doesn't do enough to be terribly useful and less you're not paying enough attention… at which point you shouldn't be using it anyway.

Surely 'speed-adaptive cruise control' is an oxymoron?