From all I've seen of Kurtzman's own art, it's sketchy and unattractive. His great strength was in layouts and having a point to make. But even with Will Elder, Al Jaffee and Jack Davis (no Wally Wood, though), the HUMBUG results just strike me as lukewarm. My guess is that Bill Gaines (that loveable nut) put more suggestions and corrections into Kurtzman's EC work than is usually thought. But then, I wasn't there and it's just conjecture. (I tend toward synergy to explain great art, writer and editor and artist all working slightly from different angles.)