Due to time constraints, I can not add a lengthy synopsis of "The Vulture's Prey" (The Amazing Spiderman #64) and am going straight into the analysis. The gist of the issue dealt with Spiderman battling the Vulture while only having the use of one arm due to an injury.
 

The injured arm "gimmick" is more than, well, a gimmick in the story. Actually, it really shows the true brilliance of Stan Lee. Lee understood that you could not tell the exact same story issue after issue even though that is what most comic books did from the 1930's to the 1980's. Most comic books involved a villain of the month storyline that generally worked well. But, in order to make a comic more compelling, there needed to be a few spins on the traditional storyline. Giving Spiderman "amnesia" during a classic Dr. Octopus storyline was one such way this was achieved. Having Spiderman fight the Vulture with only one arm was another unique method. Sure, you knew Spiderman was going to win in the end. With the broken arm gimmick you didn't know how he was going to win. This is what made something as simple as a book length fight scene incredibly appealing.

Also, this storyline adds another unique dimension to Spiderman. The character clearly has no quit in him. He won’t give up no matter what. Yes, fighting the Vulture with both arms is tough enough. Having to fight such a dangerous an psychotic villain with only the use of one arm is insane. Yet, Spiderman does exactly this because he is so driven. He understands the consequences of non-action and can not bear the thought of not confronting the Vulture.
 

So, forget about the actual narrative for a second and think of the impact such an approach to the character has on its reader. The reader walks away seeing even more character development in a superhero even after five years of publication. Considering that some superheroes had been around 20+ years with NO character development whatsoever this obviously sets Spiderman away from the crowd to a great deal. This is why the character grew to be such an icon and this is why "The Vulture's Prey" remains an unheralded great storyline from Spiderman's early years.