I watched this show on a whim for two reasons. First, there was an interesting cross between One Punch Man and Dragonball that I found rather amusing. Second, I wondered how they could make a show out of something that sounds like it would get boring really fast. It seems that at least from an action standpoint, they have you covered.
Animation:
The animation score will definitely vary based on the viewer. If one expects intricate details and choreography as in Unlimited Budget Works, cough FSN, then they'd be pretty disappointed here. However, compared to the author's original web comic this is quite a few levels up. The story takes place in a rather casually named City Z, which along with a bunch of other lettered cities are often under attack by various enemies of humanity. Expect generic landscape that reminisces of the backgrounds in early Japanese renditions of Godzilla or Ultraman. A good deal of emphasis is placed on the various heroes, contrasting the cool and focused look of Genos with the plain and rather blase look of Saitama. While Genos would pass as a fine protagonist in many other shows, One Punch Man is rather unique for adapting such a plain and simple character as the lead.
A large portion of the show consists of action sequences showing various heroes fight random antagonists, often to be defeated after an arduous struggle. This is where Saitama often steps in, quickly finishing the antagonist and proceeding to go home. Basically, the show gets away with entertaining you mostly with fights between antagonists and other heroes, like Genos, rather than the main protagonist. This kind of makes sense as otherwise the episodes would be like five minutes each in length. The contrast between Saitama and the other heroes also shows in their fighting style. Whereas the other heroes use very flashy moves or weapons (such as Katanas, baseball bats, mechs, telepathy, etc.) Saitama uses his "normal punch." The irony is that the flashy moves and weapons often have little impact on the antagonist while Saitama's punch turns the antagonist into gory pieces of flesh. Yes, expect a fair amount of gore as antagonist and Genos are both often torn to pieces.
Sound:
The show starts with a guy fitting screaming "One Punch" followed by a heavy rock piece; it's not my choice type of music but fitting considering the crazy action nature of the show. The ED is more of a cool down piece though it doesn't really tie in to the show. The BGM was fittingly engaging though no particular melody stood out.
This mostly-male cast does a fitting job giving life to the various personalities of the heroes. Kaito Ishikawa does a good job of giving Genos a cool vibe, despite the number of times he gets trashed. Though honestly, I was most surprised at how convincingly Aoi Yuuki does her tsundere role.
Story:
This isn't a terribly complicated story, and really one of those where attempting to rationalize what is happening will only end up killing your brain cells.
So there are these cities that somehow deal with continuous bloody massacres and are tasked with funding gargantuan reconstructions. Somehow, the people of these cities are stupid enough to continue living in these easy to attack places where likewise brainless antagonists show up looking to just terrorize society. Luckily, the stupid people are stupid enough to somehow fund/support a Hero's Association that dispatches various heroes to deal with threats. Heroes and villains are both classified based on supposed ability and risk, respectively. Often, the stupid bureaucrats of the association underestimate the ability of the antagonists and end up with weak-sauce heroes valiantly being defeated, only to be ironically saved by the lowly-ranked Saitama.
What it really comes down to is a relatively episodic progression that does get a bit repetitive; an antagonist appears, heroes are sent and defeated, Saitama comes in and one-punches his way to the ED. This rather boring baseline is spiced up by changing up the heroes and antagonists that show up and by attempting to weave in some themes in the story. For instance, there is a rather ironic comparison between Saitama's simplicity (not to mention his rather simple routine to get strong) and the complexity of all the other heroes. There is the blatant poke at bureaucratic infighting and the "image" of a hero. And there's Saitama's rationale for being a hero- not for fame, not for fortune, just cause it's something he wants to do.
In summary, your mileage will depend heavily on what you're looking for in the show. If you're looking for a contiguous plot with a point to it all, you're going to be rather disappointed.
Character:
While I will give credit for developing Genos and Saitama, there isn't really any level of depth with any of the other characters. Some of the supporting characters, such as Onsoku no Sonic, are developed to an extend only to be completely unused later in the show. Don't even get me started on the throwaway antagonists. There is some creativity in uniting heroes of various levels of ability (I thought Kamen Rider was particularly humorous) but that's really about it. Furthermore, disregarding Genos' multiple upgrades, all of the characters are totally static- it's all just interactions (mostly with fists) rather than development and growth.
Value:
If you're looking to scratch an action itch and don't really a detailed or explicated story line, by all means knock yourself out (pun intended) with this work. If you're looking for something with some depth to it, this might not be your choice show. That said, the base content is quite enjoyable if you ignore the multitude of unanswered plot holes and cookie cutter characters and antagonists. I'd still consider this more of a shonen work than a seinin piece. It's not the next DBZ and not quite the same kind of satisfaction as something like Birdy Decode or Gurren Lagann, but it's still an impressive work considering the origins of the source material (if you have no idea what I'm talking about you should read up about the author). At the least, it helps the rather lackluster diversity of anime works coming from Japan recently.
