They later extended it on the Xbox 360 to allow you to link in your Windows Vista machine to stream your MP3's straight to it
Playing Halo 3's campaign to Queen was a great experience back in 2007
The Xbox 360 expanded on the feature in some neat ways -- if you had an iPod or other portable player, you could plug that in via USB, it supported generic DLNA shares (so you could play music from Kodi/XBMC running on a PC), and some (most?) games would flag cutscene audio vs. in-game audio, which would allow the system to pause the user-provided audio and fall back to the game's soundtrack for cutscenes.
It also had global settings for controller vibration, inverted camera.. perhaps some others? I really miss those in future generations and on PC.