Looks quite cool. CGI has turned out to be a really wonderful thing for Japanese movie makers, since they have the imagination, but not the budgets to equal or surpass Hollywood.
This is I think at least the third incarnation of this show/character. I think there was one in the 70's or early 80's and then a series of OVAs in the nineties which are available dubbed. The OVAs are pretty good, sort of Terminator meets Greenpeace/ZPG. In the OVA at least, Casshan's father commits the classic error of building a powerful robot to preserve the enviroment, and as if you didn't see this coming - He decides that the best way to do that is by wiping out humaninty of course. Builds a giant army of robots and starts to massacre humanity and only Our Hero - Casshan, can stop them. But to do so his mind has to be put into a robotic body, thus causing many angnsty moments as he goes agonizes over the old "Am I becoming what I hate".
Just saw it. It looks amazing but suffers from clumsy plotting, and the action scenes are rather blah. Quite a pity. It definitely looks better than Sky Captain but the plot and one-dimensional characters bog it down too much.