Let's put his personal life/family dysfunction (which clouded any other aspect of his life) Aside, As an actor, Ryan was Not in the league of Robert De Niro, Al Pacino and the likes, But he was Better than Robert Redford, Warren Beatty and Clint Eastwood.
He was brilliant in Paper Moon (he didn't even get an Oscar nomination for that role), Barry Lyndon and The Driver and later in Irreconcilable Differences and Chances Are. Sue Mengers said she had always struggled to get Ryan good roles even at his peak during the 1970s, and he usually settled to do crappy movies just to work.
Walter Hill, director of The Driver movie, said "I think Ryan gave a very good performance, I was very disappointed that people didn't particularly give him any credit for what he did. To me, he's the best he's ever been."
Let's discuss Ryan O'Neal the actor and the reasons of his career's early demise.