If by customization you mean changing key bindings, prompts, colors, adding new functions, well, you can change that. If by customization you mean setting what

If by customization you mean changing key bindings, prompts, colors, adding new functions, well, you can change that. If by customization you mean setting what happens when you write invalid glob, how much you can store in the history, whether prompt beeps on error, whether integers starting with 0 are octal, what regular expression engine is used, and so on, feel free to use zsh - it's great, really, after you configure everything, that is - fish shell won't let you change that by design. This is not a flaw - author believes that configuration is the root of all evil (and I agree with him).