zsh is relatively large compared to bash. and bash is large compared to sh, rc, tcsh, etc. if there are space and memory constraints, size is relevant.
the path to "user-friendly" shell nirvana (i.e. interactive use, not scripts) can be achieved through use of a library like editline, without installing a huge, "kitchen sink" package like zsh... if size is an issue. make the shell cmd line behave like the editor you know well.
the path to "user-friendly" shell nirvana (i.e. interactive use, not scripts) can be achieved through use of a library like editline, without installing a huge, "kitchen sink" package like zsh... if size is an issue. make the shell cmd line behave like the editor you know well.