How stable is the latest MRTK3 preview?

[IvoFelix]

My understanding is that it was mere weeks away from an initial release before the team got laid off, so it should be pretty stable already right?

I'm starting a new AR project and MRTK3 could probably allow me to reuse some code from an existing VR project with XR Interaction Toolkit or at least put my familiarity with that toolkit to good use, since MRTK3 is built upon it.

Can somebody who has been trying out the previews comment on the current state of MRTK3?
What components are still unimplemented or unstable? With some luck they might not even be relevant for my project.

Thanks in advance.