Most of problems I encountered while writing this came from Swift's interoperability with Objective-C. It can often be difficult to work with and takes a while to get used to. I actually think it would be worth developers considering porting their existing Objective-C libraries to Swift for this reason alone. That said, I don't think developers should start porting their App Store apps yet. It still feels very much like it's in beta and some functionality hasn't been implemented (such as static class variables). Despite this though, I think Swift has a huge amount of potential, and once things really kick off with it, we'll probably be seeing a lot more developers writing apps in Swift than in Objective-C. The language really has a lot to offer over Objective-C in my opinion

PS: hi kevin