I've used it for 3 months over the last couple of years.
18 months ago, it was like riding with a 14 year old. Most of the time it was fine, but it would just randomly do something dumb.
Like 4 months ago (the only month I paid), we signed up because we had a bunch of long trips. I think this was v13.9? It was really good. The only problem I ever had was that I felt like it didn't give enough time to switch lanes before exiting. One thing I liked about this mode, was that you could set your maximum speed. So even if I had it on the most aggressive mode, I could have it limited to 80mph. That is no longer available.
Dec 2025-It was about perfect, it even parked for me. Unlike before, you can now control the aggressiveness on the steering wheel, while you're driving. The modes are sloth, chill, standard, hurry, and Mad Max. Hurry is good on the interstate, and standard is good for me in town. It's at the point now where I'd say it's safer than the average driver. But then you have little things that happen like driving along on 235 and you see a monster pothole. I'm going to swerve a little to avoid that pothole, the Tesla will not. I have seen it swerve(safely) to miss a bunny, that no human would have noticed in time. I'm sure this last bit is going to be the hardest to perfect, and there are a lot of things each driver does that they think is right, but is different than FSD would handle.
I can tell you that when it comes time for me to trade in my Kia in a couple of years, I won't buy anything that doesn't have the ability for FSD. Right now, Tesla is the best at FSD (among car makers), and it's not really close. I've heard that Nvidia has some plans to make something to compete, but I think that's just talk. Tesla has billions of miles traveled to learn from.