Update: After having all kinds of stability and performance issues with VirtualBox on the Win8 Release Preview, I decided to try Client Hyper-V again. Guess What? They fixed the networking issues!! Your clients can now use bridged networking without MAC address conflicts. There is still no graphic acceleration, having it installed breaks other virtualiztion software (although a quick bcdedit can fix that temporarily). I have modified things below accordingly.
If you were considering ditching VirtualBox for Client Hyper-V in Windows 8, well don’t do it just yet (unless you are having problems with VirtualBox). Enabling the Hyper-V hypervisor has performance and stability issues with host applications,
there are all kinds of issues with the networking, it just doesn’t perform all that well, and there is absolutely zero graphics acceleration. And if you enable it, other Virtualization software will not work right.
If you remote desktop into your VM you can at least get sound, but on my relatively well endowed machine, the remote desktop was sluggish – more sluggish than RDP over the internet.
Despite Hyper-V being a low-level hypervisor,
VirtualBox is blowing it out of the water in all respects. The networking is rock solid, performance is screaming(something changed from CP to RP, or some updated in VBox, cause the performance hasn’t been so hot), and you get sound and 2d / 3d acceleration(This doesn’t work at all on my machine) (Oh, and you don’t have to boot to an IDE drive)
Hopefully some of this gets worked out in future releases