I primarily got the Watch Ultra after being disappointed with Watch 6 battery life. As it was a much bigger battery I expected much better life.
I've been disappointed so far, getting barely 3 days between charges.
However, after the update the other day, I'm pleased to now be getting over 4 days!
The biggest drain on battery I've found is the 'remote connection' feature. I haven't noticed any issues when it's switched off, I still get all messages, updates etc.
Just thought I'd share.
Have a great day!