My car got the update some time around 7:30AM ET, I installed the update about a half-hour later, and the update was installed in about 1.5 hrs. The iPhone app notified me both that the update was available, and when it was finished. First thing I did was go for a drive to test out the autopilot. Here are my thoughts...
1. It will work on pretty much any road with half-decent lane markings, but it's clearly designed for highways (or at least long, straight roads without a bunch of intersections, lane changes, etc). Off highway, it often gets confused by intersections, turn lanes, and similar. Sometimes it veers off the wrong way, sometimes it asks you to take over, and it does actually get things right a surprising amount of the time. But, this is definitely a situation where you should have your hands on the wheel at all times, if you're going to use it, and be ready to take over. Personally, it's not yet to the point that I plan to use it for this type of driving. It obviously does not look for stop signs, traffic lights, or any traffic control devices aside from speed limit signs, and this greatly limits its value off the highway (which it was never intended for anyway).
2. On the highway, it works very well, better than I had actually hoped. The nagging is minimal, and really is probably just when it needs more information. I drove for about 20 miles on the highway as soon as the install completed. Over half of the stretch of highway I drove on is under construction, with the associated occasional veers in lanes, less-than perfect lane markings, changes from concrete to asphalt, closer than usual traffic, evidence of old lane markers, quick patch jobs, etc. I decided to see how good the system was and from the time I got on the highway to the time I got off, I did not touch the wheel (although my hands were close by, particularly earlier on). The system only made me grab the wheel twice, and both times were a location that I had always anticipated it would not be able to handle. It was the same spot in each direction, and it's an area where the highway veers rather abruptly from old highway to new highway - an area that I've always had to slow down and be careful to steer around correctly. Otherwise, it handled the long construction zone perfectly, including several areas that while relatively straight, didn't appear to be marked well, and I was pretty sure it'd make me take over. It also handled all of the curves without issue, aside from the one exception I mentioned that would never be seen outside of a construction zone. I stayed in the fast lane and avoided any issues with it trying to veer off an exit lane. In use, I'll probably just stick to the middle or left lane when using auto-pilot. By the time I got off the highway, I was very comfortable letting it do the driving.
3. The feel of auto-pilot may take some people a bit of getting used to. It's not exactly how you'd drive, but it's very good. It can't see as far ahead as you or anticipate as well, so it may take the outside of a turn instead of the inside, may move out of center slightly depending on road conditions, and other various quirks. But overall, it does a good job of staying centered, certainly is not bouncing back and forth between the lines. It was actually impressive how accurately it shows where you are in relation to the lines in the instrument cluster, and even shows where the car ahead of you is in relation to the lines! When I was looking down for a second, I thought it was off since it was showing the car in front of me slightly off to the side of the road. Sure enough, I looked up, and the guy was just coming back into the lane. I had been worried about it's ability to stay within the lanes, especially in anything other than perfect conditions, given how poorly the lane keeping assist had previously seemed to work. However, you should just forget about whatever you thought about lane keeping assist, because this is nothing close to similar. As mentioned above, it did a very good job, with almost no nag, on a less-than-ideal stretch of highway.
4. The TACC seems to be much better. It is a lot smoother to slow down or speed up when cars enter or exit your lane. In this situation, it drives much more similarly to how I'd drive. Again, not perfect, but very good and good enough that I never felt the need to take over.
5. The instrument cluster interface is actually not bad in practice. I would like the energy graph to be a little more detailed, but it's functional. I don't miss the time or temp as much as I had expected, given that they're still present on the top of the 17" screen. Yeah, the clock app is ugly, but I don't feel I'd ever need to use it. The one thing I do not like, however, is the loss of the little lines which were always present to show you your speed and the speed limit. It was always very clear to me if I was above or below the speed limit, and would trigger me to adjust accordingly. Now, although the speed limit is displayed at all times (looks like a speed limit sign) and you can see what speed the TACC is set to, there is no indication if you are set to over or under the speed limit. You have to look at 3 separate places - the speed limit indicator, your actual speed, and the speed the TACC is set to. This sounds minor, and maybe it's something I'll get used to eventually, but I don't like it. It's just not nearly as intuitive.
6. Related to above, it does not automatically adjust your speed when using autopilot, which is a shame. I see no reason it couldn't adjust your speed up or down as the speed limit changes. You can already do it just by pulling the control stick towards you for a second, but it should be automatic (or at least optionally so).
7. I do not particularly like the flat interface for the 17" screen. It's already been addressed elsewhere based on the beta builds, but you lose functionality in the climate control area and I just think it overall looks kind of cheap. The only thing I do like about it is how the controls for the navigation map are translucent, and you can see the map behind them. The media player app is also more functional when full-screen, although I do not like it's half-screen appearance. Didn't get to test out if album art issues have been fixed, but not holding my breath on that at least until 7.1.
8. Auto-parking seemed to be useless - I'm not even fully convinced that it was actually delivered in the update! See my full review further up, but I couldn't get it to work a single time. This is ignoring the fact that even if it did work well, it's only parallel parking at this point.
Overall, I think it was probably worth the wait. On highways, where it is intended to be used, it does a surprisingly great job with minimal to no nag. Even on roads where it's not intended, it does a decent job. I'd like to see a few changes made, but they're definitely on the right track, got most of the big things right, and it's probably the best implementation of auto-pilot available today. Can't wait to see where things go once the user data starts flowing back to Tesla HQ!