That's a bit of a tough one. Julia is much newer software than Octave, and it also has a lot of knowledge already of what does and doesn't work. They're already well-staffed by programming language experts. I have learned a lot about how the Matlab language works, and also a lot about how Octave is put together.

I don't have much to offer to Julia on technical terms. Octave's codebase started as pre-standard C++, and it's been a long and arduous job to very slowly modernise it. Julia has the advantage of starting modern.

I think the biggest lesson I've learned is, don't underestimate Matlab. It may be old, it may be an ugly language, but it also is gigantic, very well-funded, and everywhere. Julia and Octave are approaching Matlab from different angles, Julia by providing a better language and Octave by providing a free drop-in replacement, but ultimately we are both trying to replace Matlab.

Matlab users greatly value having a complete package with an editor, debugger, visualiser, profiler, and system modeller all in one. They don't generally see Simulink or the symbolic toolbox as being separate components, or indeed, as the completely separate programs that they really are. For the devout Matlab users, these conveniences greatly outweigh a better programming language. Going further, many Matlab users don't even consider their activity "programming" at all, and in recent years Matlab even writes the code for you if you just push a few buttons.

We're seeing some academics slowly switching over to Julia. This is great. The Mathworks knows very well that captivating young, malleable minds in university is how you get loyal paying customers, namely, the future bosses of these newly-molded minds. Julia is doing a good job appealing to profs. I am optimistic that within five years or so, new generations of Julia-trained graduates will slowly spread the love of the new language.