When I first heard about the Pi I thought it would be revolutionary but now you can pick up Android tablets for less than $50 which use a similar chip, already include a monitor, RAM, a drive and are functional out of the box. In addition I can just go to a shop and buy one whereas the Pi had (and maybe still has) a massive wait. I imagine it would be possible to run a Linux distro on most tablets without too much trouble too. For a media player you will need to spend a little more to get a tablet with a HDMI out.