In the current mobile climate apps can make or break a platform. Just ask Blackberry. While Android phone manufacturers can undercut Apple on price, it is in this app ecosystem that I believe Apple still has a major advantage over its key competitor.
Apple's unified system is a key draw for developers
The unified nature of iOS means developers know that if their app works on one iOS device, it more or less works for all users (iPad/iPhone scaling and old model limitations both accepted). With Android, developers have the double whammy of having to build for, and test across, multiple operating systems as well as multiple hardware setups. Quite simply, it is significantly easier to design and build a successful single Apple flavoured app than to make sure your app works in a variety of Android flavours.
Of course many apps are replicated across both iOS and Android, and there is little doubt that this will continue as more and more Android powered handsets are sold, but it is still noticeable that there remains a steady stream of significant apps made just for the Apple ecosystem. Just the other day, for example, I saw that Betfair, a major UK betting site is encouraging its users to place bets with its app during events, and that app is only available for iOS. They are far from the only ones.
Furthermore, there can be significant delays releasing on Android. For example, the hugely successful Temple Run game came out on Android a long time after we iOS users were all addicted.
Interestingly though, in terms of pure numbers, Android is actually winning. Back in April Harry McCracken from Time reported that it was Android, not Apple who was winning the numbers race, reaching one million apps in the Google Play store first.
However, on Lifehacker -- not a site whose writers are known for being Apple fanboys -- Adam Dachis says that iOS has a “bigger and better” variety of apps. The key point Dachis makes is that there is the potential for making more money in the "goldmine" of the app store, driving better development. There is also no point in having a load of apps that people don’t use or like, and here Apple continues to thrive, too, with ReadWrite detailing greater user satisfaction from iOS users.
Apple’s app development platform isn’t perfect. Lots of developers complain about the company’s control freakery. However, if I were a developer, I’d know the platform I’d rather be working on.