I'm not an expert on Asian cinema by any means, but I have probably seen more than the average man on the street (although I work in a film department of a library, so the streets round here are actually full of film buffs), so I'm not coming at this film with no background knowledge or understanding of the culture it arises from, as it were.
Anyway... From Battle Royale to Spirited Away via Akira, Tetsuo, Audition, Crouching Tiger Hidden Dragon, The Happiness Of The Katakuris, Zatoichi and dozens of others, the examples of Asian cinema that manage to filter over to a western audience (praise be to independent cinemas and the "miracle" of DVD) seem to suggest that the people who produce (and, by association, make up the audience for) these films are completely and utterly insane. Or, at the least, have a very different cultural approach to violence, fantasy and society than we do. Casshern does absolutely nothing to counter this borderline xenophobic view.
In fact Casshern takes the biscuit. Casshern is about the most mental and crazed thing I have ever seen (bar Tetsuo, but that's another story).
It's like... a Japanese version of Sky Captain & The World Of Tomorrow except informed by 80s adult comics rather than 30s kids comics - try and imagine what that means; Watchmen, Dark Knight Returns, nastiness, death, conspiracy, war, religion, resurrection - not nice Jewish kids creating clean-living aspirational heroes. It's literally like Sky Captain (and the forthcoming Sin City) in that it's an almost entirely digital production bar the actors, who were shot on blue-screen with backgrounds painted in later on a computer. It's also literally like Sky Captain in that there are giant robots and flying buildings and crazy scientists. Only in Casshern there are also quasi-religious messiahs and pollution diseases and Freudian family romance and star-crossed lovers and mutant androids and swords and guns and a train so wide it needs five sets of rails.
It's like all three Matrix films rolled into one and then augmented by a bit of Apocalypse Now (the, um, "point" of the film is that war is nasty because humans are nasty and we should all love one another, such as the point matters). Don't expect to be abe to follow the plot (it's mental), don't expect anything to make sense, don't expect to empathise for the characters, don't expect those enormous unexplained happenings to ever be resolved (why is the lightening bolt that is a catalyst to the film's main event an ACTUAL SOLID OBJECT? for example), don't expect the slow boring bits to be profound in any understandable sense. In fact don't expect anything other than a bonkers trip into an alternate world that veers between joyously symbolic fakery and unsettling realism, where a superhero zombie who can fly and do cool karate chops that split giant robots in half saves the world only doesn't, really, and instead, possibly, flies off to a new planet with his girlfriend to start again. Or something.
In short, good fun, but absolutely ridiculous.