Guile-Cairo is complete, wrapping almost all of the Cairo API. It is API stable, providing a firm base on which to do graphics work. Finally, and importantly, it is pleasant to use. You get a powerful and well-maintained graphics library with all of the benefits of Scheme: memory management, exceptions, macros, and a dynamic programming environment.
Guile-Cairo 1.10.0 has been released. This is a maintenance release.