A great performance by Robert Downey Jr., an early Katie Holmes role and a small part played by a heavily made-up Mel Gibson do their best, but they don't save this film from its sheer weirdness. Four words: lip-synched ensemble musical numbers.
When it cut to action from the novel our hero (Downey Jr.) has written, I really liked the visual style, and overall, the story told in flashbacks is well-done, near-perfect noir, in fact; when it steps outside the frame, however, and tells the present day story - with the characters from the books interfering in some strange meta-fictional way - it loses its momentum, getting downright hammy in places.
And then, there are the musical numbers...
An ambitious film, but I'm not sure I mean it as a compliment; Joe Baltake probably said it best when he called this one an "interesting failure." Check it out, if for no other reason than this: it's different than most everything else you're watching.