This library is still in active development. API may see changes, while ABI compatibility is not guaranteed at all. As such, it's heavily recommended to use this library as a git submodule if you'll decide to use it, or at least explicitly specify commit you're using.
While source code is in Vala, any language that supports GObject-introspection bindings (Python, Lua and many, many more), as well as C/C++ can use this library.