I have tried a lot of Multi step checkout plugins, but most of them doesn't work or have bugs.

This plugin really works (on WooCommerce 3+).
It is complete and it's regularly updated on woocommerce changes. Support is really handled.

As a real skilled developer (N°1 on StackOverFlow for WooCommerce tagged questions) I can say that this is a good plugin.

Much thanks to the author.