Now Microsoft has made alot of improvements with the latest RemoteFX feature in 2012 R2, (Now i’ve written a bit of the requirements of remoteFX before –> http://msandbu.wordpress.com/2014/05/18/remotefx-and-vgpu-2012r2-requirements/)
Most important thing to remember about remoteFX vGPU is that it is only supported on Enterprise Client OS (Therefore Windows 7 and 8 Enterprise SKUes)
It also requires Hyper-V 2012 / 2012 R2 installed with Remote Desktop Virtualization Host role installed.
It also requires a graphics card, http://blogs.msdn.com/b/rds/archive/2013/11/05/gpu-requirements-for-remotefx-on-windows-server-2012-r2.aspx
In my case I have Dell R720 with S7000 Firepro card. Now you need to install the FirePro drivers for 2012 R2 on the host.
After that you need to check for enabled the GPU to be used for RemoteFX. 
After that you need to have a virtual machine installed with Windows 7/8 enterprise Generation 1, and you need to attach a RemoteFX adapter to it. NOTE if you are running Windows 7 you need to update integration services!
Note that the number of monitors and resolution define how much video memory is dediated to the virtual machine. You can see the vRAM allocation overview here –> http://blogs.msdn.com/b/rds/archive/2013/12/04/remotefx-vgpu-improvements-in-windows-server-2012-r2.aspx
Now when you have configured a virtual machine with RemoteFX you can boot it and RDP to it.
To be sure that you are using RemoteFX you can look at the following.
DXDIAG:
Device Manager:
Now to have optimal performance you need make sure that TCP/UDP 3389 is open, since RemoteFX uses UDP for most of the graphic transport. Now remember thet vGPU only supports DirectX acceleration (not OpenGL)
there are custom performance counters within the virtual machine to monitor, if for instance network is the issue/ performance locally or something else.
Now Microsoft states that RemoteFX is now supported on WAN and yeah it does work, but not at the same performance that Citrix or VMware has at the moment. ill come back with some more detailed tests on remoteFX vGPU comparted to 3D vGPU HDX later.