[kps]

I use it, both interactively and for scripts.

One reason is that its `getopts` makes it very easy to provide full short and long option processing with help messages; script boilerplate is something like

    usage=$'
      [-1]
      [a:a-long-option?Help text]:[number]
      [b:bool-long-option?Helpful text]
    '
    while getopts "$usage" c
    do
        typeset opt_$c="${OPTARG:-1}"
    done

Another is that the final command of a pipeline runs in the shell environment, so that you can do things like

    bunch |
      of |
      commands |
      while read some stuff
      do
        RESULTS[$some]="$stuff"
      done

and then use the $RESULTS. That is fairly painful in bash; basically you have to wrap the entire rest of the script in { … }.