I can't see using TACC. Who's using THAT? Without auto-steer and without ability to change lanes by tapping the turn signal, it's just a cruise control, and not very useful.
I use TACC largely because of the shortcomings with AP. I imagine basic AP owners mostly use TACC because they have no way to change lanes without stopping lane-steering, and then starting it back up after the lane change. There is also probably a small subset of people who simply feel more comfortable with TACC.
Probably the number one thing I despise about AP is the tendency for it to recenter itself in the right lane during a merge point. I'm certainly not the only one that's had this issue. Every time there is a new firmware upgrade people claim it's been solved, but I've never seen it disappear completely.
As to what frustrates me the most about TACC/AP/NoA is not frustration that it can't do more, but frustration that what it does today isn't more consistent.
I certainly have enjoyable drives, but I also have drives where it fails at very basic things. Now in a way I might have to temper my expectation because most of my TACC/AP/NoA driving is on road trips. It's much more difficult to go 400+ miles of different variables versus 50 miles a day over the same variables every day.
There is also the potential that there might be something wrong with an individuals car. So that kind of thing does add variability to the fleet.
Here is a good example of that possibly being a factor.
Autopilot performance after upgrading to FSD : teslamotors
This individual complained of the EXACT same thing that I despise. But, they claim they don't have any issues with a Model S with EAP. They didn't check the firmware versions so I don't know what role that played.
I'm not very confident of that because I've seen plenty of youtube reviews (who are pretty "it is what it is" types) from people doing extensive NoA testing where it's not able to score a good grade. In fact the last one I watched the reviewer didn't even bother testing it any further because NoA failed to get out of the passing lane, and I think there were some other issues as well. So they were just going to wait for those things to be fixed.
In my own testing I'm just flabbergasted by what doesn't meet my expectations which I don't feel are all that high.
TACC isn't smooth on P3D. The bench mark is the AP1 Model S I had previously.
Lots of people including myself report false braking with TACC or AP (I don't think false braking events are any different between the two). The bench mark again is AP1 Model S.
NoA is highly dependent on maps so that one I'm a little more forgiving on, but some of the decisions it makes is downright mind-boggling
Smart Summons is a complete joke. I even went through the effort of updating the OpenStreet maps for the location I was testing it at work. The update vastly improved it, but it still failed to consistently work properly (10 times was the goal). I gave up on it, and haven't tested it since then. This one might be worth checking since it's been months.
Smart Park we're still waiting on, and in the meantime all we have is autopark which can be really frustrating.
Unconfirmed lane changes is broken as reported by a lot of people (excessive delay compared to what it used to be)
Pedestrian detection for AEB failed to get the top grade from IIHS
Pedestrian detection didn't pass the AAA test, and didn't get the best score either.
Don't take my word for any of this. Just spend some time watching videos of people doing extensive testing. It doesn't meet even moderate expectations.
It's also important to point out that progress on FSD has stalled out. It's currently undergoing a rewrite of sorts. So I could easily be complaining about something that will be completely different in 6 months.