It looks like VMware just released Fusion5, I currently run 4 and I find it a stable application. I think some of the new features, improved graphics and support for more ram are nice to see. I couldn't find any reviews as it was just released but I may upgrade in a few weeks if I start seeing positive comments on it.
http://www.vmware.com/products/fusion/features.html
http://www.vmware.com/products/fusion/features.html