The beta has been great with quite a few enhancements. This is no sales pitch just my comments after playing around with it for some time. The Mental Ray renderer is simply stunning. Perhaps I will place a rendering up here after the weekend.
Here is a link to the PDF on features:
http://www.discreet.com/docs/products/3dsmax/3dsmax6_techspec.pdf
Cheers,
-Shaan