I have one of these in my room. It works really well.
Pros: The sound quality is really good. It doesn't take much of a server to support it. (I run it off my 800Mhz celeron. Normal load is about 2-3% and about 23 MB of memory). The server software is open-source perl with an active development community. The server runs on Windows, Mac OS X, and pretty much any linux or unix. The display is really bright and adjustable.
Drawbacks: No built-in control buttons (IR remote only). You really need to use the server's web browser interface to fully control playlists, etc. At just over 8" wide it's too large for car installs limited to the standard DIN width.
if you wanted to put one of these in a car all you need to run from the server PC to the player is a crossover ethernet cable. The server could sit in the trunk, out of the way.