Apple's App Store has reached its one-year milestone. The Cupertino, Calif.-based company one year ago launched the online store for its iPhone and iPod touch and has had great success offering users applications that do everything from calculate nutritional information to games that shoot cartoons out of volcanoes.

The question on many peoples' minds remains how to gauge the App Store's success.

"I can confirm more than 50,000 apps are available for download on the App Store and that over one billion apps have been downloaded since launch," said Simon Pope, an Apple spokesperson.

While the number of apps downloaded isn't something to ignore, Apple, which receives 30 percent of revenue from each app sold, has never revealed what the profits are from the popular store. Because Apple has remained tight-lipped about profits and the cost to maintain the App Store, it's not clear if it has been a financial success for Apple.

Apple's Bruises

Not all has been perfect in the 12 months since the store's launch. Developers have complained that Apple doesn't like competition and has blocked any app that might compete with its own iPhone programs.

They have also criticized Apple for being too rigid when it comes to deciding what is offensive. Developers have further complained about the app-approval process, which is often described as controlling, confusing and slow.

As a result, some developers have accepted Apple's terms in order to continue to develop for the store, while others have boycotted Apple's gatekeeper ways by developing for others.

"About 90 percent of apps are low-quality and unacceptable, and apps have been free as opposed to having fees," said Robert Enderle, principal analyst at Enderle Group.

In the year since its launch, the App Store has had to face competition from others.

"The Apple app store has been the property to set the pace, and they are the ones that everyone is trying to emulate," Enderle said.

Standing Out

Finnish phone maker Nokia launched its Ovi Store in May. Ovi's model is similar to Apple's and gives developers 70 percent of the revenue from applications sold.

Apple also now has to compete with Google's Android Market, Palm's App Catalog, and Microsoft's Marketplace for Mobile. And if that's not enough in the mix, Research In Motion launched App World for BlackBerrys.

"Other app stores seem to be learning from Apple's success and mistakes," Enderle said. "It has had a major impact on the segment."

Analysts think Apple has succeeded in one of the two things it set out to do with the App Store, and that was to sell iPhones. The other is its revenue model, about which little is known.

"Apple is good about not talking about something unless it has something good to talk about," Enderle said. "I believe revenue from the App Store is not yet meeting expectations."