Everyday, hundreds of apps are submitted to the app store... I do mean hundreds. I'm sure there are days where they come close to the 1,000 app mark. Long gone are the lazy days of putting an app out there and hoping that it sells. Unless you actually still do that... Bad idea... market the thing!
There are books well written on the subject. For the most part, the people looking to make money quickly will walk away angry, "What a waste of money!" This process is really is a marathon. Sure, there are your quick success stories, but for the most part the App Store is a puzzle to us all since Apple does not share sale figures.
In Apple's defense, it is a very regulated market. It's not easy to get an app approved. The problem for many people is the agonizing over the time it takes for the app to be approved. On average, 3 weeks seems to be the normal waiting period. That can make you sweat, because they might not even approve what you have done. That's three weeks of waiting to find out whether you're good to go, or you need fixes. In some cases, that really can kill an upstart business.
The rumor is that the larger companies don't have this problem. I don't work at Gameloft, so I cannot address that kind of thing. Just keep in mind that it's good to go through an approval process, because it means you're in a more trusted and regulated marketplace for selling apps. But, don't be shocked when you end up having to put out updates for your app in order to calm your customer's 'bug' complaints. The more time that ticks by without 'necessary' updates to your app, the more agitated your customer base can become. Remember that it's not because of your technical inabilities to solve bug problems that the update needs to get out there, but rather Apple's lengthy waiting periods for approvals. Try using your company website to reassure fans or 'haters', and address their compalints.
Lets hope Apple makes us all spend less time waiting. Cheers, Joe