From the angular, opaque eyes to the way the gloves, shoulders and chest and all integrated in one smooth, flowing pattern, Spider-Man broke the mold when it came to coolness. I've read that Ditko always tried to design his costumes so that, even if a panel only displayed an arm or a leg, it would still be instantly recognizable. This is most evident in Spidey's case. With but a glimpse of the distinctive red webbing pattern that has been driving inkers mad since 1962, we are immediately aware that Spider-Man is on the scene.Go ahead and send him hatemails for leaving out Batman. There's no Superman too.
Spider-Man's costume is unique in that it was designed within the story to be cool, at least in the eyes of its creator. Peter Parker needed to whip up a flashy costume for his big debut on the Ed Sullivan Show, and the end result really looks like something a 17-year-old nerd would sew together in his aunt's basement. Pete threw together some blue and red tights, spiderwebs attached at the armpits (!), a big corny spider on the back and a mask that left his face completely covered (presumably to hide the ravages of acne that are all too common during those awkward years), and somehow ended up with perhaps the second most recognizable superhero costume in history.