If Clint Eastwood had retired after Gran Torino, it might have been one of the most perfect endings to an iconic actor's career. Walt Kowalski is like Harry Callahan or number of Eastwood characters from his past only, like the vessel they're protrayed through, older. He's the crusty, cynical tough-guy who deep inside is a bit softer and has a warmer than you'd expect heart. Which is the truth we see revealed in Kowalski over the course of this movie as he befriends and helps the Hmong kid next door. There might be enough of these movies to constitute an entire subgenre of friendship films: one involving an older guy who learns a little about life while teaching a boy to be a man. It's a friendship story and even what you'd call a feel-good one despite the violence and negativity surrounding it. The film aims for authenticity though I think bits of it will be seen by posterity as dated, false hollywood depictions.
Maybe the later movies kept him busy but this is where Eastwood's career as an actor should have (and in a sense did) end.