The most obvious use case is to replace absolutely anything you'd ever use OpenVPN or IPSEC for. Building on that, Tailscale is so simple that you consider things you wouldn't have before just because OpenVPN would have been so painful to set up. It has fine-grained access control and it integrates with SSO.

It's good for home use, but --- and I am bias I guess because of my background --- where it really shines is corporate connectivity. If I joined a company as a security person and it was running some horrible OpenVPN access VPN for its dev team right now, one of my top action items would be to replace it immediately with Tailscale.