Hyper-V in Win8 is really quite good. Its missing a few features from The server Version, like live migration for example. But all the main components are available so its a fully functional virtualization platform.
Hyper-V wont automatically use NATing so you will have to set it up yourself. To do that create a virtual switch of type 'private' in H-V. Then in Windows network configuration, on the adapter that's connected to the internet go into its properties and choose 'sharing'. In the drop down list select the Hyper-V virtual adapter.
id write a more detailed explanation but in on my phone.
Im currently running my little VM eco system at home on Server 2012 as well as a few test machines on the Win8 version and i can't fault it, (apart from no inbuilt NAT feature for the client version.)