Reading the original SPIDER-MAN run by Steve Ditko in black and white, a few things stand out to me:
It's astonishing how you can really see the influences Ditko would later have on Frank Miller, something that isn't so so obvious on the outset, especially if you read Ditko in color, which obscures Ditko's play with light and shadow and some of his graphic solutions (stark patterns, etc.).
Block out Stan Lee's copy, and the comix “read” infinitely better! The flow is smoother, and SPIDER-MAN suddenly becomes a far more “adult” comicbook.
Peter Parker is so unlikeable. In a funny kind of way, it's almost as if his character is an amalgamation of the most unlikeable aspects of his creators; Lee and Ditko themselves.
The tone of it is so different to Kirby's FANTASTIC FOUR, so much that it's beyond obvious that Lee's only involvement was slapping copy on stories (and characters) he had little involvement in creating. Not very good copy at that. I mean, if there is one atrocious and terribly outdated thing about any of these comix, it's the dialogue and captions.
Calling these “comix” is pretty accurate. They are so weird and off-beat in comparison to the far more sterile output of DC around the the same time, which at that point had already taken on a far more corporate approach to its output. Rewind 20 years earlier, and you find that at its onset, DC's comix had weird and oddball written all over them (when the actual creators of the characters were making the comix), sharing qualities with what we'd later identify with zines and very indy comix.
All corporate comix today are essentially fanfiction. Not only that, but it's fanfiction at its worst: assembly-line productions, overseen by editors and catered to fit company policy.