Beta3 is primarily focused on SDK changes, including support for Visual Studio 2010, refactored code examples, more detailed documentation, etc. Among common enhancements are improvements in the computational meshers which can now process non-manifold shapes with shared faces.
V2.1 features Parasolid-XT export support, color support in VRML and X3D formats, numerous user-requested enhancements in GUI and much more. Check the CHANGES file for details and visit the download page. Let us know your feedback shortly so that we could address it before the production release which we hope to deliver within a few weeks.