I’ve only read one of his books, Cuba Libre, but I must tip my hat to him because he has influenced other writers I have read at greater length, namely Carl Hiassen and (indirectly) James Ellroy: Hiassen for the cruel humor; Ellroy for “colorful” language. I could be wrong but that’s how I see Leonard’s influence in those two. Most people are more familiar with his books being turned into movies recently: Get Shorty, Be Cool, Out of Sight, Touch and Rum Punch which Tarantino tweaked into Jackie Brown with Leonard’s approval.
Originally, he started out writing Westerns back in the Fifties when that was the preferred fiction of Hollywood, TV and the public at large. He switched over to modern-day crime stories with his anti-heroes having a heart of gold later on his career; see Chili Palmer and Jack Foley.
Out of Sight is an awesome film. I’ve watched the DVD about 20 times.