Not sure if you're asking relative to other options, or just in the absolute. I'll respond to the latter.

Some of my complaints below may have remedies - please feel free to inform me!

When Android Auto loads up, it shows me a tile with the current weather. In Fahrenheit. I want it in Celsius. Everywhere on my phone I've set it to Celsius. In the Settings (I think multiple ones). In the actual weather app. But AA will show it in Fahrenheit.

And why show me that tile at all? I don't want to see it. I can't disable it. In my Android Auto settings, I removed it from the list of apps. It still shows up. Why can't I control what apps launch?

Why is there always a navigation app loaded? I don't want it on by default if I'm just going to listen to stuff. Nothing should be loaded by default except the launcher menu. I should be able to configure on my phone what I want autolaunched.

It eats up too much battery. Why does it need to eat so much battery if all I'm using it for is to listen to podcasts? With regular Bluetooth, it barely consumes battery.

Waze sucks on AA compared to just plain Android. I can't, for example, send an ETA via AA. I can't even do it on my phone while connected to AA.

Why does the air vent fan speed drop dramatically when I get a call? Why does the climate system even know I'm getting a call?

If I connect my phone via USB cable, why does it insist I connect via Bluetooth? I can go to Android settings, have Bluetooth forget my car, and when I plug in the USB and launch Android Auto, Android will connect to Bluetooth. I Googled and apparently this is intentional. I find it very hostile.

That's all from the top of my head. I'm sure I can come up with plenty more.