I really like the monster creation segment, in that it's simple (mechanics wise) and yet very powerful (in invoking images in the players' mind). That's something I like in games: when the players are able to affect the world greatly without even knowing any rules!
I also like the Supports-idea; it's not what I know, it's the fact that I know that's important (the former being the skills system in d20, and the latter yours).
The layout, as others have mentioned, feels really professional (there are two blank example boxes though on pg. 13 and 17). One nitpick is that the front page says "West Side Horror", the next "West Side Horrors", on pg. 5 it's "Horror" again, and it seems to hop between the two throughout the document. I'm only mentioning it since an inconsistency that small really stands out in an otherwise professionally looking document!
And I know and/or assume that the audience for this game is people who are already familiar with RPGs and the terms, but another issue I have is on pg. 14 where you mention dice, more exactly the terms "6d6" and "3d6". The game is written in such a way that I guess an inexperienced player could understand and run it without any hassle. I believe a small explanation (a sentence!) of what "xDy" means would straighten out that last question mark for any new player.
Good work!