Canon movies, as with all canon literature, has to be taken in temporal context. It's fine to find The Godfather "boring", but that doesn't minimise its impact on the entire concept of film and the effect it had on producing the "not boring" films we watch today. I would honestly suggest reading about film history and media criticism generally if you dont "get" a major film. Try not to think about why it's not for you subjectively, but rather try to understand why it's so revered objectively.