What are the pros and cons of allowing Google Play store to automatically update apps? Automatically update apps on my Android phone:

Upsides:


Apps get new feature, bug fixes, performance improvements, etc.


Downsides:


The UI layout or some features that I am already used to changes. Sometimes I am regret to update the app due to this.


So I set Google Play to not update the apps automatically on my old phone. Now I am getting a new phone. Are there any other pros and cons to these settings, and what are some ways to mitigate my concerns?
Apart from being automatically updated, and even if you apply updates manually, you only know about possible disadvantages once the update was done. So my recommendation goes in a different direction, namely: being able to restore the state before the update was applied, so you can "roll back".

For this, I recommend using AppMonster (or rather AppMonster Pro, as the Pro version can do all required stuff automatically in background, so you cannot forget it). This app automatically creates a backup of each app's .apk file whenever the app is installed or updated. It also takes care about only keeping a configured number of backups, so you don't risk running out of space. If you don't like an update, you then can simply launche AppMonster to restore a previous version.

I'm using AppMonster for years already, and can heartily recommend it. And as to your original question: I have auto-updates turned off, so I can manually decide which updates I want and which not. For some apps, I prefer the version I'm currently using for reasons like removed functionality, less overhead, and more.