Its much more responsive in my experience. It supports a wide range of options, has gestures for controlling certain settings (i.e. brightness and warmness) allows position syncing with other KOReader devices (Another reader,Android App for example), browsing and downloading from OPDS catalogs and Calibre instances, Downloading saved articles from Wallabag instances.

Honestly the only thing I use the stock Kobo software for is to launch KOReader. It does everything the stock software does but better.

I should mention, you install KOReader and its dependencies on top of the regular firmware, not over it. You can use them side by side