More than anything else it reminds me of Synecdoche, New York. Not for plot, but for the way it illustrates its creator's uncomfortableness with fiction, and life, and the relationship between them.
As an actual story, it's laughably weak. As a musing on comics mythology, fiction, and the relationhip between the author and their character it's marvellous.
I'm now looking forward to the release of Flex Mentallo, which (IIRC) builds on this idea.
On the other hand, I'm also glad to Morrison grew out of this, and that his more recent comics largely valued plot over existentialism (particularly for things like We3 and All-Star Superman. Obviously Seaguy is still heavy on the subtext. I'm hoping that gets finished at some point.)
Original post on Dreamwidth - there are comments there.