Of course install it on a non-primary, non-daily-driver device because as far as I can tell, is unstable and slow, not what you’d expect from a stable release, but hey, you know that, it’s beta software.
So, why install it??, as far as Beta 3 it’s kind of usable with some minor glitches and slow response of the keyboard, but you’ll get the updates and will known when it is ready for you to use with your iPhone or daily-drive device.
You can get used to the mayor changes that it introduces… did you know that the keyboard layout for non-letters keys changed??