From time to time I hear some complaining within the iOS ecosystem about Apple's rules about in-app purchases. Of particular note is the requirement that digital products must be made available through the in-app purchase system. Companies can also sell the product through their own web sites, but IAP must be an option the price must be the same in both places.
The restriction means that it's not possible to do things like buy books through the Kindle app. Amazon doesn't want to pay Apple's 30% cut on IAP sales, and I don't believe the IAP system is even equipped to handle a catalog of Amazon's size. Instead, users have to navigate over to Amazon's web site (without a link from the app, mind you) and buy the book there, then re-open the Kindle app.
It's a fair criticism, but I've also run into a few situations where I'm glad Apple's rule exists. I'm a baseball fan (let's go Red Sox!) and for the last few seasons I've subscribed to MLB's excellent MLB.TV streaming service. When I first signed up a couple of years ago, it wasn't possible to sign up via in-app purchase, so I created my account through the MLB website.
MLB automatically renews your subscription every year, and this year I wasn't so sure I wanted to keep my subscription, so I logged onto the website to cancel. I had to hunt around a bit, but I finally found a cancellation form. But I ran into a little snag: Submitting the form always seemed to fail with a mysterious error. (That's actually an improvement over previous years, when there was no cancellation form and you had to hunt for a phone number hidden in a block of fine print to end your subscription.) I had to email MLB's customer support in order to confirm and complete the cancellation.
A little time went by, and lo and behold, the baseball gods seduced me again. This time I decided to sign up through the Apple TV, since that's where I watch most games anyway. The process was as simple as picking the subscription period I wanted. To access MLB.TV on other devices, I can just use the Restore Purchases button instead of having to enter my MLB login credentials. Even better, now I know that if I want to cancel, all I have to do is disable auto-renewal in my iTunes account. MLB won't be involved at all, so I don't have to worry that their systems will mysteriously fail. An added bonus is that I have one fewer place to update my credit card information if my number changes.
In this case, Apple's rules on in-app purchases led me to have a better experience. Signing up was far easier than entering my contact and billing information on MLB's web site, and I don't have to log in to each device separately. While Apple's billing system isn't always perfect, I personally have never had trouble with it, and I trust Apple more than most other big companies. Apple says that their priority is to create good experiences for their customers, and this is one case where their restrictions on in-app purchases did just that.