getting it setup:
I just tried it out last night and with standard 10.5 drivers, you will get 99% of it working without problems.
if you want total control over key mapping and macros, you'll need a 3rd party driver (i used controllermate, but it isn't necessary at all for most people)
that said, there is exactly one button that will not work with apple or 3rd party drivers, and that is the white windows key in the bottom right. i do know the developer of controllermate is trying to fix that.
useability:
if you're looking for a small keyboard and mouse for computing, this probably isn't the solution for you - i doubt there is one.
if you want a remote control for running itunes/front row/etc as a home theater or similar application and only need itunes navigation, searching, light web surfing on the tv, this is a godsend.