Good point, rgdot... As you note , the GUI isn't really changed very much, there are no new features (though a bunch of new stuff is promised for v.4.x). Upgrades are pretty cheap - $19.95. However, as I noted, I don't think I'll jump - I'm happy with my current workflow.
I can report, though, that I found the beta to be very stable and it worked well under Win 7 64-bit.