This episode brings into the spotlight of the show a lot of new characters, some of which will later either become recurring stars, or even better, villains.
The most important one of them is of course Wilson Fisk, the Kingpin. Even here, in his first appearance, it becomes clear that he is "the man behind the curtain", the one who is always in charge and everyone works for him and ready to destroy anyone who dares to oppose him.
Other characters introduced here include Symthe, who won't be treated as a "real" villain until much later, and Norman Osborn, the man who will become the legendary Green Goblin. His "business" relationship with the Kingpin (in which the latter is manipulating him only to get his own way) will become the trigger for him to become the Green Goblin in the first place.
The plot of this episode is more humorous than usually, but that is fine, since the show won't have too many light-hearted comical episodes. Flash Thompson wearing a Spidey costume only to scare Peter, him being captured by the Spider Slayers, Peter trying to save him, etc.; all these are some of the funniest scenes in this episode. The dialogs between Peter/Spidey and some of the other characters is also hilarious. Plus his one-liners, which always made Spidey unique.
Also the animation is great, just like in the previous and upcoming episodes. The show had great visuals, and considering how many action scenes and robot-like creatures appear on the show, the animation only makes them look even better. The show may have tons of other robots in later episodes, but none of them will look as good as the Spider Slayer from this and the next episode.
The end is really well done, not necessarily a cliffhanger, but foreshadowing the next episodes. The Kingpin once again does what he does best: manipulates people. He tricks Symthe into believing Spider-man killed his father, and offers his help to avenge his father's death. Overall a superb, exciting episode, which has everything, from hilarious moments to giant robot fights.