The config file for managing basically the whole OS is amazing to begin with. Also the fact that the system is freshly rebuilt every update is neat too. And there is something where if a certain package requires a certain version of a library it will be installed alongside the current version just incase. Avoiding dependency hell.
About troubleshooting, the official wiki for nixos got made this year so it finally will start to make sense to new users. I used to use arch because of their amazing wiki but now I use nixos since there is an active effort to make it easier.