One Punch Man is just Saitama doing GSP's "I am not impressed with your performance" in every episode, and it is awesome. Sad it ends, but they went through a -ton- of manga issues in 12 episodes. There's generally a lot more buildup for each monster and how strong they are, and then they get to try a bunch of shit on Saitama and he just dodges/blocks/looks confused for multiple panels. Then the eventual one-shot happens, but each fight is like a manga to itself, let alone the other heroes doing their thing, or the story building up what's happening while Saitama is just wandering around lost or confused. This season went through like 2/3 the current released chapters, so probably a bit before we see a second season =|