I thought the ending was spectacular. It was short and simple, it showed how despite everything he did to safeguard his family and existance, he ended up tragically alone and blind. His daughter was dead, he was probably hated by his (ex)wife and son, and he retired to a life of geriatric mafioso whereupon he ultimately died. The scream is an awesome scene, moving itself, but coupled with the final images of Michael and the flashbacks, the ending did what the entire movie was meant to show: The Death of Michael Corleone.