It's great fun. It's also kind of dumb... no, that's not fair. It's a good show. It's just uninterested in messages beyond "COOL FIGHT!!!" or perhaps "there's no apocalypse so bad that some bastard wouldn't make it ten times worse to make money from it".
That's okay, though. I don't expect ever to rewatch this show, but it's a laugh for twelve episodes.
The worldbuilding is both fantastic and mental. This show is basically hot-blooded shounen anime meets Looney Tunes. It's a post-apocalypse Japan that's just one more disaster away from Mad Max, with a desert environment and ecology that's gone insane. Mushrooms are a weapon of mass destruction and a "Mushroom Keeper" is the world's most feared terrorist. Fish and whales fly from the sand, cops ride iguanas and our heroes ride a giant intelligent crab that can beat up tanks. There are weaponised hippos and giant snails. And that's just the start of it. There's a plague called Rust with no known cure that was started by the exploding space alien that trashed Tokyo. The prefectural governor of Imihama is a gangster whose enforcers wear comedy bunny heads.
Our heroes are Bisco (abrasive shounen hero and swaggering outlaw) and Milo (doctor and genius who annoyed the governor by treating poor people for free). Both will have their female fans in-universe (especially Milo), but we know where their hearts really lie. Ahhhhhh. Partners forever. They also both have family. Bisco has a slightly mad-looking mentor (Jabi) who looks like a half-witted grandad but is actually as cool as hell. Milo has a hot cop sister (Pauu, romanised in the subtitles as Pawoo) who's dying of Rust but is cooler than everyone else in the cast put together, including the evil governor who's voiced by the coolest voice actor in Japan (Kenjiro Tsuda). I love the way this absolute monster is so jovial and friendly that he even drops baby talk into his dialogue.
This show ends so conclusively that you'll be convinced the story has reached its ultimate peak and could have nowhere else to go... until it proves you wrong. (These twelve episodes adapt the first volume of a light novel series that's still running and has released nine volumes so far.)
The story's not particularly deep, but the worldbuilding's wild and the plot has some genuine surprises. I particularly like the slower first few episodes that help establish the world. It's a well-constructed story, much like the 19th century concept of the well-made play. It's ingenious, full of energy and with a plot that never stops roaring. The characterisation is simple and never far away from archetypes, but these people are vivid, entertaining and always great fun to watch. (And capable of being off-the-scale cool.) If you're in the mood for post-apocalypse crazy stuff, check this out.