The sad truth is that this film is almost certainly doomed to fail, whatever the reason. It's hard to tell whether the pro-Keanu crowd is more or less than the anti-Keanu crowd - they'll probably just cancel each other out.
Something will go wrong - the writing, directing, acting or even the budget (low budget can be good, but a big company cost-cutting never ends well). It'd be great to say that this film has a chance, and it does, but it's not a very big one, given the history of western anime-adaptations. There are dozens of other anime/manga titles waiting for adaptation, most of which are on hold to see how others will do, so this film will end up having an impact on the film industry, whether it turns out to be good or bad.
I'd still have preferred Hugh Jackman. He doesn't have the right build though, so I'm still wondering why I thought of him first...