Command-history works the same way

Pipes and angle bracket operators work the same way

Setting env variables inline works the same way

All the familiar basic commands for getting around (cd, ls, cat, etc) are present and work the same way (same flags, same output format, etc)

All the little things that trip you up when you just try and use cmd.exe to do something simple would work the way you expect them to from bash. Everything that doesn't translate falls back to the normal Windows behavior. 80% of the benefit, 20% of the effort/complexity