It works, I will say that much for it. You can download TV shows and watch them. The video quality is good with no pixellation, but apart from that it is a pretty paltry product considering that it is seeing the light of day after four years of development.
Shows are downloaded as .wmv files to the Documents and Settings\All Users\Documents\My Deliveries\iplayer_live directory from where they can be played in the Windows Media Player as well as the BBC player. This makes me think that they can probably be played in the Media Center app as well, but I've not got a machine in the office I can test that on. I've tried playing files across a network, but the DRM kicks in and prevents it.
It is a Windows XP only program, but there is a trial and error how-to here, from someone who has got it working on VISTA.
Could try harder.