Childify Me is used in WordPress for creating a theme that doesn’t get overwritten when your main theme is updated. When installed, folders and files are created that let you add scripts and CSS to your site. This saves you from having to re-enter CSS etc, that will get lost if you update your main theme.
Installation is simple, and then a single click to create all the files you need. When you go to customise CSS within the theme, you’ll be changing the child theme, and not the main theme.
Personal experience
This plugin was needed for a theme that was regularly updated, and works 100% fine.
Use cases
When you need to retain the edits you make to a WordPress theme’s CSS
Cons
None!