Here are some choices I think are interesting as new languages:
Elixir : interpreted / scalability / concurrency / fault tolerance/ friendly community
Rust : compiled / close to C speed / memory safety / concurrency
Elm : compiles to Javascrtipt / functional / runs in the browser
That said, the edge cases are few and far between. TS is a fantastic language to work with.
If you're writing server-side code for Linux/OSX, probably not quite yet. The language is nice, but it's only been available as open-source for a day now... the ecosystem you'd need to be productive in Swift isn't there yet.
(On the other hand, if you'd like to be involved in building that ecosystem, now's probably the time to jump in.)
I wouldn't want to use it for anything substantial, but if IBM's already hopping on the bandwagon it seems like a good language to learn for heavier use later on.
In particular, the Swift Programming Language ebook isn't a bad starting point. The IBM Swift Sandbox looks like a nice little interactive environment to complement it, though, if you don't have access to a Mac to run Xcode.
It's open source. Works on Linux, Mac OS X, Android, iOS, Windows, etc. It has a good ecosystem and tooling built around it already but you can also tap into the C# ecosystem, if necessary.
It compares really well to Swift: http://www.slideshare.net/ScottWlaschin/swift-vslanguagex but even without that comparison, it's worth a look on its own.