Fish more or less just works. It has a lot of sensible defaults out of the box, and you can be extremely productive with it right off the bat. It also forgoes

Fish more or less just works. It has a lot of sensible defaults out of the box, and you can be extremely productive with it right off the bat. It also forgoes compliance with POSIX intentionally, with the rationale that POSIX can sometimes be an obstacle. So you get things that are dramatically better than how they work in other shells, like the prompts. Instead of injecting stuff into envars, you just make a function that echos your prompt out. Same goes for right prompt and most of the other configuration stuff; its all function driven