well it is to me at least. A drive this afternoon; on the way out the car sits quite happily at 65mph on a 60mph road on AP all the way. The return journey however the car decides it doesnt know the speed limit at one point and slows the car to 45mph. Not a big deal? Well tell that to the poor chap who was behing the car following me, when my car slows suddenly without any brake lights in the middle of a series of sweeping curves, causing the car behing me to over-react to this completely unexpected and unreasonable event (no brake lights but noticeable deceleration as the AP gently but firmly reduced speed in the middle of a curve ffs), the car behind him then has to panic brake and slides out sideways into the oncoming traffic. How the hell there wasnt a sizeable accident can only be down to sheer luck. To say the chap was (entirely understandably) pissed when he came past me later would be an understatement. The righteous here will undoubtedly chime in about how you shouldn't follow too close, which I will pre-empt by saying that to my opinion everyone was driving entirely sensibly. But abruptly slowing down in the middle of a curve without warning is inviting trouble. Sorry Tesla, I understand why you felt the need to introduce it, but this is a dumb feature that you have to improve the implementation of, and quickly before it causes accidents.