Rowling hoped to break away from her authorial typecasting by moving into crime writing under the name of Robert Galbraith (I wonder if the Galbraith was taken from the famous economist J.K. Galbraith?). Unfortunately her secret was swiftly blown. But as Robert Galbraith, she has a very different authorial voice. If you hated Harry Potter, you may well love Robert Galbraith, he is not the same voice at all; if you loved Harry Potter, you will revel in Rowling's superb story-telling skills, and sly humour.
Her private eye, Cormoran Strike, who has also had a change of direction - war-hero turned detective - and his side-kick, the naive but enthusiastic Robin - are as engaging a detective duo as you can hope to meet; and the first in the series The Cuckoo's Calling is sharp, witty, full of character, and has a great plotline. I was completely swept up in the action and absolutely loved it. For a first foray into detective fiction they don't come much better than this. It seems to be a milieu in which Rowling feels completely at home. Long may it continue.