I really like the simplicity of the Swift syntax. If you write "swifty" code, it almost reads like a poem in comparison to other languages, but is still extremely powerful.
I was able to learn basic iOS Development with Swift in just a few month from no programming experience at all and it also allowed me to learn a lot of other languages based on my experience with Swift.
Moreover I like that it was made open source and everybody can contribute to make Swift a even better language!