Sym is still early in the beta testing process, but it's now at a point where most of the main features are done.
It's far enough along so that you should be able do some useful things with it and it's far enough along to get feedback.
If you have feedback, you can send an email to firstname.lastname@example.org or use the Send Feedback menu item in the Help menu.
Up to this point, the emphasis has been on the code in the application itself. As a result the libraries are still in need of a lot of work.
In addition to improving the existing libraries, more libraries are in development.
The main features planned for Sym in the neat future include:
In technical content it's fairly common to put mathematical symbols or small expressions inline with the text.
Future versions of Sym will include this capability.
Export and import
Export to LaTeX and HTML has been implemented in this version, but are not thoroughly tested and don't handle all of the objects that you may need.
Other exporters are planned.
The functionality to create and manipulate matrices is only partially implemented. It's possible to create matrices and to add, subtract and multiply matrices.
Everything else (determinants, inverse of a matrix and so on) has not been implemented yet.