First impressions: significant speed boost and noticeably smoother 3D rotation to the point that I'm not sure how often I'll use Boot Camp now. Very surprised that Ambient Occlusion and Realistic Materials works in virtualization. I was having issues with this in Boot Camp as the NVIDIA GeForce GT 330M is not on the approved/supported list.
Overall - realistic materials and smoother 3D views make this worth the upgrade.
It's actually so nice that I think even GuyR would be impressed.
All the best -
Phil