I'm loving all the changes to CarPlay. The ability to use my phone and not have it effect what I see on the car's screen is fantastic.
Re: the simplicity - remember that you don't have to use the new multi pane screen. If you want the screen with only apps, or just the app you are using, it is...
The thing to remember about betas - it isn't just about them being buggy, etc. It's that apps you currently use might not work with the new software yet. The OS might work fine but the apps you rely on may not...
Also, what is rock solid and working on this release might not be the same way...