Although I have only played with swift, it looks quite pleasant to use. However as a developer it is always required that you look outside the language to see what libraries are available, what platforms it can be used for and what is the future feasibility of it. I can try to answer these:
1) It only really has libraries available to it on Apple's Cocoa platform. I.e otherwise you are going to be spending most of your time writing binding layers for every platform you use it on. For example bindings would need to be written for it to use OpenGL or SDL on the Linux platform.
2) It is cross platform because it uses LLVM as its underlying technology but there is very little support on non Apple platforms. IBM was looking at getting it running on some of its enterprise operating systems but lets be honest, we wont be writing games to target them ;)
3) Lifespan... Nothing from Apple really has the best lifespan but it does look like they are committed to Swift. That said they are not going to be rewriting the OS to use Swift rather than Objective-C so you might want to stick with the latter instead. (You can also use SDL and OpenGL directly from Objective-C on non-Apple platforms ;)).
So sometimes it isn't about how easy the language is. It is about how useful the technology (and legacy) behind the language is. Otherwise, lets be honest, C would not be second from the top on the IEEE and TIOBE language stats ;).
To be honest Swift is no longer an Apple only technology. It has been open sourced and as well as the IBM sandbox there are a few others. There are also two other non LLVM compilers that support swift including ones for .NET, JVM and Dalvik.
There are also several Swift website frameworks already in development or already in use targeting both client and backend development.
However another reason why I dislike Swift is that because of the its dumb name (there were already a few IT technologies around called Swift before Apple used it) if you google any of these you get lots of unrelated content.