I have a model 3 and have tried FSD several times (Tesla regularly offers free one-month trials), and I've only found it to work well for long highway inter-city drives. I'm generally an early adopter and was eager to try it. It did _not_ work well for urban driving -- at least not in our city -- it acted like a new, nervous driver. I felt uncomfortable the entire time. I convinced my wife to try it for a day and she hated it and will never touch it again.
If you can't trust it 100% for urban driving, then FSD provides almost no benefit over more basic adaptive cruise control, early collision detection and lane departure warnings, etc. You still have to sit there and focus on the ride. The idea that I can now sit in the backseat and catch a nap or do some work or whatever, is still sci-fi at this point.