The story follows a group of about a half-dozen Minimum Holders. Most of them work for a private detective agency called Hamatora. Individual episodes are mostly about agency jobs, usually relating to bringing some kind of rogue Minimum Holder to justice. Most of the characters have odd names (Birthday, Moral, Three), but you get used to that fairly quickly.
There's a larger background story running throughout as well, involving the creation of artificial Minimum Holders, a grisly process involving the harvested brains of natural Minimum Holders. The reasoning of the head villain for doing this gets convoluted, but basically revolves around how he wants everyone to be equal. He goes on at length about granting power to the powerless, and how even the most powerful need equals. It's not the most compelling reasoning, but hey, he is the crazy head villain.
There are flashes of the usual anime silliness, such as when everyone ends up on Okinawa on a beach fighting with melons, or the guy whose power turns a health spa into a seduction zone. That stuff is fairly minimal, though, and often followed immediately by some sort of remark that makes fun of it.
I can't say that Hamatora breaks any new ground, but I enjoyed the ride. The ending wraps up the story but leaves the viewer with a cliffhanger. I'll be watching the sequel Re:_ Hamatora in the near future to see what happens.