The 30% fee is steep, but conversion rates using in-app purchase are astronomical compared to regular webpages with a credit card form. Everyone hates it (developers, I mean), but it works very well.
In case anyone wants to know why this is: it's because
1) I don't have to enter credit card information
2) Apple allows me to cancel subscriptions in a central location as soon as I sign up
If your service forces me to auto-renew my subscription, I'm probably not gonna buy it.
