The standard focusing screen with this camera is rubbish. It shows too much in focus and pictures shot wide-open have very different boke and DOF compared to the viewfinder.
But this new focusing screen, the Canon EG-S, appears to fix that. It’s designed for manual focus, insomuch as any focusing screen without a split-prism can be used for manual focus, but it’s much snappier than the standard screen. Focus comes in and out quickly and sharply, and the boke/DOF issue is gone. I’m told it’s dimmer. Impossible to really tell.
In any case, Canon viewfinders are rubbish compared to my old Nikon F2 and F3. Cinematic viewfinders you could compose a symphony on.