Hyper-V requires a 64-bit system that has Second Level Address Translation (SLAT). SLAT is a feature present in the current generation of 64-bit processors by Intel & AMD. You’ll also need a 64-bit version of Windows 8, and at least 4GB of RAM. Hyper-V does support creation of both 32-bit and 64-bit operating systems in the VMs.
Hyper-V’s dynamic memory allows memory needed by the VM to be allocated and de-allocated dynamically (you specify a minimum and maximum) and share unused memory between VMs. You can run 3 or 4 VMs on a machine that has 4GB of RAM but you will need more RAM for 5 or more VMs. On the other end of the spectrum, you can also create large VMs with 32 processors and 512GB RAM.
As for user experience with VMs, Windows provides two mechanisms to peek into the Virtual Machine: the VM Console and the Remote Desktop Connection.
The VM Console (also known as VMConnect) is a console view of the VM. It provides a single monitor view of the VM with resolution up to 1600x1200 in 32-bit color. This console provides you with the ability to view the VM’s booting process.
Read more at source - http://blogs.msdn.com/b/b8/archive/2011/09/07/bringing-hyper-v-to-windows-8.aspx