It’s essentially a GUI for Docker. It has its own quirks that, in my opinion, don’t match Docker’s UX and can make it more complicated to customize deployment. But Portainer can make multiple environments or dozens of containers easier to manage. e.g. I do most of the actual work using compose yamls but use Portainer as a reference to organize subnets, ports, and volumes. Or if I’m unsure what the problem is and just want to see all the details of each container faster.
Running a Debian VM with Docker solved all those issues for me. I set the arrs root /data folder on my NAS to mount with CIFS at boot. It works so well with a ceiling of 4/8 cores and 12GB RAM I’ve moved all my containers to it and mostly just use Proxmox for monitoring and reliable backups/images over NFS.
The only issue I’ve had in the last year or so took me about 30 minutes between realizing something was wrong and fixing it: Make sure you put your CIFS credentials file in a folder accessible to Debian’s main user account or a power loss will break automount until you re-establish the link with a root user. Or create a locked down arrs-only user on your NAS so the CIFS command can include the username and password with less concern.