Michael has been the good guy who refuses to be in the family now he has to revenge his father's shooting
Very tense scene, the audience knows what is going on in his mind so it builds slow tension, will he do it?
He is filmed in shadows as we watch his dark mind work.
A lesser film would have had drama music here it is a train that is rushing through his mind before he pulls the trigger
where Sicilian is being spoken so the conversation, which you do not understand, does not interfere
Godfather is an art film, very subtle