Definitely not as an aftermarket accessory. I happened to have one in my other car and i turned it off,it was braking the car without my input,just couldn't get use to it.
Adaptive cruise control is awesome, especially on heavily-traveled freeways where the flow is less than the speed limit. You just set it on 75mph and let the car figure out how fast everyone else is going. It will fit itself right in. It's relieves just as much fatigue beyond regular cruise control as regular cruise control is less tiring than full-time driving. If you have a long intercity commute, say Dallas to Austin to San Antonio on congested I-35 or Dallas-Houston on I-45, or use the New Jersey Turnpike or any number of other East Coast highways, it's worth every penny.