In systems where I find myself in the shell, I tend to prefer the shell to everything except certain system configuration tasks (I like the shell for things like tweaking network settings, but dislike it for things like printer config, for example), and for actual software dev (IDEs still win for me).

Once I feel I can buy into the shell, I'll probably go all in. Until then, I try to use Cygwin to avoid having to switch to a *nix box when I just want to use a simple admin utility or maybe test something out in the Python REPL, but otherwise I just tend to switch when I want to spend a work day on something.