Is simply the best mediaplayer that has ever existed period. It is fast, easy to use and features several interesting features such as the ability to play .rar files containg .iso files or other kinds of media.
Originally developed for the Xbox it has now been moved to Linux, Windows, Apple-TV and (most interesting) Live-CD / USB-stick which should open the opportunity for hardware manufacturers to start building cool media-center-machines.
There is no repository available (yet) for Intrepid, but in the forums someone claimed that the hardy repositories works fine. So go to:
System / Administration / Software sources and hit the “Third-party software” tab. Add these two, one-by-one:
deb http://ppa.launchpad.net/team-xbmc-hardy/ubuntu hardy main
deb-src http://ppa.launchpad.net/team-xbmc-hardy/ubuntu hardy main
Close and reload and goto Add/Remove applications where