A "Vala vs Java" and/or "Vala vs C#" would be helpful
So the biggest difference from C# or Java is that there is no VM. It is mostly syntactic sugar over C and GObject.
At least, this was the case last I paid attention 15 years ago.
Ha! Ain't that the truth :-)
It touches on a big problem for new language development in that there are barriers to entry at getting workable in a new language, but employers don't want to use them unless they can hire for them, and they can't hire for them unless people use them, but people don't use them because they can't get hire'd to use them, rinse and repeat.
I actually first heard of Vala just a few days ago when I was looking at a C#-related PR[1] for highlight.js:
> This fails the tests as the Vala default.txt is recognized now as C#. However, Vala is very close in syntax to C#, and the default.txt also seems to be valid C# so not sure what to do about this.
https://wiki.gnome.org/Projects/Vala/ValaForJavaProgrammers
Imagine going to a link called docs and finding the first 2 links are about what you ask for :D
Maybe I'm alone, but my immediate thought when seeing a new language, with fairly familiar syntax, was "why is this different than Java". And if that's my first thought, it probably makes sense to answer that question immediately rather than talk about vague things like Productivity and Open-Source.