Well, at least I am amazed. I took a brief look at Julia a few years ago but since I understood it to be somewhat derivative of GNU/Octave (or Matlab) and R, and since even though I use GNU/Octave and R I don't enjoy these languages, I only gave Julia a very short look.
Fortunately, a current customer uses Julia so I have been ramping up on the language and I very much like it. A bit off topic but I would like to give a shout-out to the O'Relly Safari Books Online service which I recently joined when they had a $200/year guaranteed for life subscription price (half regular price). I am reading "Getting Started with Julia" by Ivo Balbaert which is fine for now. I have "Julia for Data Science" by Zacharias Voulgaris and "Mastering Julia" by Malcolm Sherrington in my reading queue. When learning a new technology having up to date books available really is better than finding information on the web (or at least augmentation to material on the web).
I very much like the tooling for Julia. Julia is a new language but there are already many useful libraries available. Julia uses github for storing modules in the standard library and the integration works very well, at least on Ubuntu Linux. So far, I have been happy just using GNU/gedit for development. I haven't tried Julia on OS X or Windows 10.
The Julia repl is great! Color coding and auto completion are especially well done.
I like just about everything about the Julia language except for 1-based indexing of matrices. Oh well.
Julia is readable, functions are first class objects and programming in Julia is very "Lisp like." With optional type hints (mostly in defining function arguments) Julia is a very high performance language. I love developing in Ruby but I do dream of much higher performance. Julia does not seem like a complete replacement for Ruby (for me) however. That might change.
In addition to doing work with Julia, I have also been experimenting with lots of little coding projects: the Merly web framework (simple, sort of like Sinatra), using the standard HiddenMarkovModels library, and experimenting with a few of the neural network libraries. All good stuff.