How incredible was his directing?
Watching his movies, in particular his most famous masterpieces, but also in the minor ones, you see film artistry that you don't see anywhere else.
Only a few directors in film history come close.
Even when I don't like the movie (E la nave va) his style superiority is undeniable.
The best description for his style was given by Pasolini, who said that Fellini didn't simply shoot movies, he said "Fellini? He dances!"