My biggest question is, what if I publish this game myself? I have a developer account, a game at about 75% completion, 6 apps on the app store, and a decent plan to monetize it already. The only thing that would be nice is the press for winning, or placing. That and a free trip to beautiful California. What turns me off about publishing through this route is the first $1k is yours, and 30% after that. So, after Apple and MGWU, I would be left with 40% of all sales - something I don't think the publicity would offset, even long term. My gut says this hinges on the fact that I'd have to publish through MGWU for it to count as an entry.
I'm also wondering about guaranteeing 10,000 installs. That would be nice, but I have over that on one of my apps and that doesn't really equate to blips on the App Store internal marketing/searching system in my experience.
EDIT: After reading the detailed rules, it looks like you do have to publish through them. And, instead of being left with 40%, I'd be left with just under 50% of the price/prices of items for sale in the App Store.
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This is probably a good deal if you can't make the art for your game, and can make the mechanics/playability fairly quickly.