If I'm reading it correctly, it would reduce the 30% fee to 17% unless you only distribute your app on third party app stores.
> Reduced commission — iOS apps on the App Store will pay a reduced commission of either 10 percent (for the vast majority of developers, and subscriptions following their first year) or 17 percent on transactions for digital goods and services.
I'm also not sure what the 10% fee applies to. Apple doesn't charge a fee if you're purchasing physical goods, only digital goods (that's why you can buy a paperback book on the Amazon app but you can't buy a Kindle book on the app). Isn't everything that could be purchased through an in app purchase or subscription a digital good or service?