Vala is an incredible project. With a relatively small number of contributors, it's turned into an easy language to work with, that can compile into shared libraries with automatic bindings for Python, Ruby, Lua, etc., and get near C performance. GTK bindings are pretty complete. With some effort (I hear -- never tried it), it can even run on Windows and OSX. Vala may be one of the most underrated Linux projects around.
What's wrong with Vala?
Vala looks interesting.
It would appear that with GTK libraries available on Windows and OSX, a port of a Vala app should be trivial. Valac compiles to C and then GCC takes over for the rest of it.
It seems like the most well-known Vala apps are managed in San Francisco by Yorba, however they're only for Linux. http://www.yorba.org/projects/
Any examples of cross-platform apps written in Vala?
the problem is that Vala is strongly linked with only gtk making impossible to use it with others ui libraries.
They needed a GUI language and decided to go for a C-derived imperative one? That's an option I guess. At least it's not Python.
The first kind of thinking is what got us into the second kind of situation.
Enjoy ...Vala.