I'm not that familiar with
The Spirit, but I kind of agree with Aerostar on the Frank Miller issue...he's a good writer, but his stories are always incredibly misanthropic, dwelling very strongly on the dark, violent and ugly side of humanity. I have no problem with that when he's working on his own projects like
Sin City or
300, but when he tries to write for other characters, he just lets that same sensibility warp them into something far more unpleasant than they should be. I'm fine with artists bringing their own style to a project, but there's a difference between that and allowing your own idiosyncracies to overwhelm the source material. I know that Miller's
The Dark Knight Returns is hugely acclaimed, but I just found it to be unrelentingly and jarringly brutal, bleak and, crucially, not very heroic, which for me kind of defeats the point of Batman entirely; I've not read any
All-Star Batman and Robin, but from what I've heard it's a similar deal.
Again, I don't know The Spirit that well myself, so I can't comment on how Miller's style would suit it, but my feeling is that even if it doesn't, Frank Miller isn't the sort to make any concessions, which for me is both his greatest strength and his greatest weakness...