What’s everyone think of Ira Levin?

Maybe he isn’t exclusively a horror author, but you can’t deny he’s helped shape the community. Anyways, I’ve been on a Levin kick lately. So far I’ve read Rosemary’s Baby, The Boys From Brazil and last night I finished The Stepford Wives. Gotta say, he’s quickly become one of my favorite authors. Thinking of checking out This Perfect Day next. Anyone read it or have other recommendations by him?