I voted "satisfied".
This is a rather new technology, so its expected that there will be some flaws. I've been far more annoyed by other new automotive technologies early in their use.
My biggest problem with it is that I'm a bit of a control freak. For example, I like to position myself differently in a lane based on what's on either side of me. The AP seems to prefer crowding the right side of the lane a bit too much for my taste. I only position like that if in the rightmost lane.
I also pay close attention to the action of drivers in the cars around me. Are they distracted? Are they checking mirrors like they are planning on making a lane change? Are they holding their relative position in their lane, or drifting left and right in their lane? Are their motions fluid or jerky? Is there someone in front of me making lots of lane changes, and how are those around him reacting? Is there someone weaving their way through traffic coming up behind me? What is their likely path through traffic around me? If that yahoo does something stupid, what are my outs?
All this goes into proactively anticipating and reacting to traffic. AP is probably purely reactive. I know automatous vehicles have a vastly better record than human drivers, so reactive doesn't seem to be a detriment.
I don't know if I will be comfortable handing over control in any kind of heavy urban traffic. To any car. Ever.
That said, I have been very happy on the performance on relatively straight rural roads. I think the current implementation works well with Tesla's Supercharger philosophy - emphasis on long distance, typically rural, interstate travel.
Edit: I also constantly scan the road surface looking for debris, potholes, fluids, and this time of year especially, wet leaves. I don't know how AP would deal with these conditions, and wouldn't want to be the one to find out.
Now that I think more about it, I've had all kinds of creatures run out in front of me on the interstate. I wonder what AP would do about deer darting across the road? Yes, I know the technology is supposed to be "assist", but I think as people get comfortable with the technology, their attention to conditions will fade.