Been a few years, and it was cool in the day, but very complex. With k8 now, not sure why one would choose Juju first. They are slightly different problem domains, but not exactly.
For automation of deployments we prefer ansible (ex. it's agent-less)
For container orchestration it's clear that kubernetes is the winner (if you have k8s deployed you don't need juju)
For managing the whole thing manage iq have much to offer.
I like Ansible and use it for deploying vagrant setups and such but I've found quite a few things broken enough that I'm wary of using it to do deploy production stuff for quite a while I had issues with apt: so much so I ended up using shell, last time I wrote a new playbook they had resolved that though so things do get fixed.