because it's that good you mean? was it a difficult learning curve?

It has a steep learning curve for sure and is extremely different with how files are organized (for good reason). If you, however like to experiment a lot and don’t want to end up unable to boot your system or care about a reproducable and predictable system configuration/package management, it is a no-brainer and very rewarding.

I never understood why one would use Nix on anything except servers

What's good for the goose!