We reached out to a few active iOS developers to get their thoughts on whether the larger screen would mean delays or a more difficult development process.
There are going to be a lot of apps letterboxed for a while after the iPhone 5’s launch. Most apps are going to be fairly easy to adapt, but the biggest delay is going to be app review.
Developers were only able to submit apps for the larger screen (and any iOS 6 updates) as of yesterday afternoon, and I bet many of them (myself included) are trying to submit their updates to Apple as quickly as possible. App review times are usually about 6–8 days, and this huge influx of app updates is likely to lengthen that significantly.
Well, iOS 6 comes out in 6 days and the iPhone 5 comes out in 8 days. Unless app review is somehow multiplying their throughput by an order of magnitude or two this week, I suspect there’s going to be a very big backlog for at least few weeks, and very angry iPhone 5 customers leaving 1-star reviews on our letterboxed apps in the meantime.