App developers have been working on iOS 5 since it was announced in at Apple's developer conference in June. That encompasses most of the summer and the start of autumn. iOS 5 officially drops about a week from today, on October 12. Was it enough time to deal with the new features and APIs that Apple has baked into iOS 5?

We want to know: what was the most difficult or important aspect of iOS 5 to develop for? From Game Center to Notifications to the new graphics APIs or iCloud, there are several new moving parts of iOS 5 to deal with. Check out some comments from prominent iOS developers below and take this the ReadWriteMobile poll.

Apple has sold 18 billion apps and paid more than $3 billion to developers. The company wants to remain in the drivers seat for developers with iOS 5.

There are several significant upgrades and features in iOS 5 that will be important to different sets of developers. For instance, the new Android-like notifications are important to a company like Pinger, which makes the popular Textfree app.

"One of the things that iOS5 does is make the notification manager better," said Joe Sipher, co-founder and chief product and marketing officer for Pinger. "The process of upgrading the OS makes it updating as easy as everyone else. It eases the testing process [for new versions of apps]."

One thing that Sipher mentioned was the fact that a new feature in iOS 5, the To-Do List manager, could take the livelihood of some developers. It is not a groundbreaking change to iOS, but there is a group of To-Do list apps in the App Store that had found a market niche Apple was not supporting. Now that Apple does support To-Do lists, the ability of those app developers to make money may be hindered.

Then there are also improvements to the way that Apple has approached Game Center, its central hub for logins and the iOS game ecosystem.

"In a way, I think iCloud is going to become the new standard for games because users will start to expect the ability to share their game save data across all their devices," said Dave Castelnuovo, CEO of Bolt Creative, the creators of Pocket God.

CasteInuovo added that there were not a lot of hard parts to develop for iOS 5 because," Apple does a great job with their APIs and they are all pretty easy to use."

As we have seen with many apps, the iOS version is the flagship before it developers port it to other platforms. Castelnuovo thinks that iOS 5 further cements Apple as the de facto platform to develop for heading into the near future.

"This is probably the biggest change to iOS that has happened so far. I do think it's game changing because there is no other mobile OS that helps developers as much as iOS 5," Castelnuovo said. "Think about it, now any developer can create their own multiplayer games or cloud storage without needing to create their own server. Servers are usually pretty expensive to support and you have to be prepared for it going down in the middle of the night or on holidays. Now Apple takes care of that for us. We can't even port these features of our game to other platforms because it would be too expensive for us. In this way Apple is making sure that the iOS versions of our game is the flagship version."

Feel free to add in any iOS 5 feature that was not mentioned in the poll. Those should be five of the biggest but was there something small that was particularly difficult? Let us know in the comments.