I am very much against the way Cocoa & Cocoa Touch work (a "ViewController" is NOT!!! a controller in the MVC sense), and Interface Builder makes me want to take a high powered rifle to Cupertino, but Swift is definitely a winner now that it's going open source.

I rebuilt a dysfunctional OS X application that was ported from iOS (obj-c) from the ground up almost entirely in Swift last year, and really enjoyed working in swift. It's worlds better than Objective C, and compares favorably with other modern languages like Go (which I also like and use quite a lot). It takes a minute and a bit of annoyance to get used to optionals, but that ends up being really nice for issues most languages let you shoot yourself in the foot on. Along with switch patterns, easy immutability, memory management, string handling, and Playgrounds/REPL make it a really pleasure.

Even with that endorsement I couldn't recommend it seriously for anyone without being cross platform / open source. Now I can say I really think it's worth learning.