A new review of Robert Skidelsky's Keynes: Return of the Master in the New York Times (plenty of other reviews on his books page there), and also Peter Clarke's Keynes: The Rise, Fall, and Return of the 20th Century’s Most Influential Economist. Reviewer Justin Fox says:

“What’s vital about Keynes today is not so much a well-defined economic
doctrine as the attitude and the tools with which he attacked economic
problems.”

Although it's very out of date now, and certainly highly favourably inclined to its subject, I still like Roy Harrod's The Life of John Maymard Keynes. It's one of the books that helped turn me on to economics.