The C2 language is still under development. However, since it is an evolution of C, no major changes are expected. Still, some new features might break current code.

Component Status Notes
Parser 90% pretty much parses everything. Needs better handling of syntax errors
Analyser 60% needs improved type checking, un-initialized diagonostics
C generator 95% some corner cases still need to be implemented
IR generator 5% basically only Hello World works (functions, strings, function calls)

So the short status would be that for playing around with the language using the C-generating back-end, it's pretty usable.