"I really don't see why the Roku has such a following beside being available to buy in the high street shops."
Have to agree with you there. I just checked out their website and from what I read it can't even access media from your local LAN. Which, for me at least, is a must-have feature in a mediabox.
Think about showing some of your vacation pictures or movies to your friends; I usually do that using my TV and the trustworthy AC Ryan mediabox.