I think Kirby excelled at drawing dynamic, square-jawed, powerful heroes, but at the time, Spider-Man was very much the slender, wiry, exceptionally agile type that Kirby just didn't handle well. He was great at depicting obvious power and strength, but certainly pre-Romita, Spider-Man was very much the wiry, athletic type. His attempts at drawing Spider-Man always just seemed clunky and boxy.