I am installing 2012 Hyper-V tomorrow on a test rig (medium spec's new server), I shall report back once I have had a few days play. I have only been using Hyper-V for three month and I really miss Vsphere, its just doesn't cut the mustard IMO.
I'm getting ready to test the new hyper-v too. I was hoping to get to it today but it's not going to happen.
Just installing it now. it will only be a couple of days alive as the machine has to go into production next week :(