Received mine yesterday. Works really well, minor irratations with the controls e.g. the big round dial in the centre not being the volume control (unless you press the volume control buttons first - in which case it suddenly changes to doing that). Had to install their squeezecenter software on the WHS, but it can run as a service so no big problem.
The remote is useless if you have a large music library, stepping through the lists is one at a time at about a couple per second. Using the dial on the box flies through and appears to page through long lists.
Squeezecenter supports iTunes integration but needs access to your iTunes library file, which I manage from a workstation so could not use. Have had to set it to scan the directories.
Has a range of downloadable plugins - unfortuantely the sexy weather display type ones don't fit on the display properly - unless someone would like to write one? It can display any info, so possibilities for a WHS addin that displays warnings?