I'm about to finally order my Y and I'm going back and forth on it.
I tried it during my test drive and it was quite disconcerting. Not necessarily that it was doing anything wrong but it's quite disconcerting at first when a car does something when you are not in control of it.
I remember the same feeling when I first tried regular autopilot and I turned it on and it instantly accelerated to the speed limit. That was scary. I've since turned on the setting where it stays the same speed when you turn it on... but there doesn't appear to be a setting for that on FSD.
FSD seems to accelerate to speed quicker than I'd like as I'm not in control. I also had my foot hovering on the brake as it did the exit and navigated to the road. It did fine. I also took over on the highway as we we're stopped behind a semi and we needed to pull into the left lane from a stop to make our exit. A challenging maneuver for a human let alone a computer. (Crazy Pasadena traffic on the 210)
Anyways I digress....
The reason I'm thinking of buying FSD is I keep cars a LONG time. I'm still driving my 2011 Leaf which I've had 12 years. We're probably going to keep the Leaf and sell the gas car so I'll even have it longer.
Since I'm going to keep it that long it might be worth getting.
My one fear with FSD is I buy it with the car and God forbid a month* or a year from now I get rear ended and insurance deems it totalled. Will Tesla let me transfer it to the new car? Who knows? Will insurance value it? Doubtful.
*2 out of 3 brand new cars I've purchased have been rear ended or backed into within months of ownership.
Thankfully never totalled but still.