Its amazing how many different experiences people have had with Android Auto.
Personally, this is one of the things that I think Google has absolutely NAILED right from the beginning. No implementation of a half-assed solution which "might" someday grow into something viable. I've loved it from the day they made it work as a standalone app.
I use a magnetic windshield mount in my car, and mount it as soon as I sit down.
Once the bluetooth connects, Android Auto starts up automatically.
One feature I wish it had...I wish it would start playing my music immediately.
I'll say "OK Google, navigate to work" to make sure I have no traffic concerns along my normal route.
If a text comes in, I get a notification of a new message. I don't like that I have to touch the screen to read it.. it should be able to be read via voice command. I CAN reply without touching the screen.
After I say "OK Google", the volume turns down to maybe 10%, so I know when it is listening
All in all, it is everything I'd hoped for when I heard they were releasing it as a stand-alone app. No need to drop big $$$ on an Android Auto-compatible head unit anymore!