The main thing it fixes for me is that I can now use a regular Logitech mouse and scroll just like on Linux and Windows. Before it scrolled too slow (on pixel level) and even when scrolling fast it went slow (no matter the settings on Mac OS). If I let the Logi MX Anywhere 3 wheel roll freely it scrolled too fast. This tool fixed the annoying scrolling issues I had.

This seems to be the main feature it does.

The other is that you can reprogram what the middle button (the scroll wheel click) does.

Same with botton 4 and 5 (default back and forth between pages).