Limitations of VDI
VMs tend to use generic drivers for video and storage. With VDI, storage presents little problem as it will be done through the SAN. For video, however, there is a real issue.
A user with an application that requires high-performance graphics, such as AutoCAD or Adobe Dreamweaver, will find VDI is not suitable for what they do. This is because the generic VM video driver is very limited. Putting a high-quality video card into the server does not overcome this because you cannot replace the generic video driver with a better quality driver.
There are other limitations for peripherals connected to the local machine. Bi-directional USB support for synchronising smart phones and other personal devices is not universal across VDI implementations. Nor is bi-directional audio support a given (needed for users with voice dictation software, for example).
Synchronisation of VMs for mobile users is still at a very early stage. Only VMware has released an early version of software supporting this. Microsoft is waiting for the Citrix solution which will be released to beta in Q2 2009.