Do you remember the days when music players just played music? It seems that they now want to show video, display lyrics, sell you CDs or tell you what else you should be listening to. When you start up Audacious your first thought will be "this is XMMS" (or WinAmp if you only recently moved from Windows). Audacious is a fork of BMP which in turn built on XMMS, so this is no great surprise.
While XMMS had its faults, its small interface was perfect if you just want to have audio playing in the background while doing something else (like writing a review of an audio player) instead of having the music player be the main event.
Audacious is fast and lightweight, but it still handles the core responsibilities of an audio player. It plays all popular formats, including MP3, Ogg Vorbis, FLAC, WAV, WMA, MIDI and a variety of MOD formats. IT also handles playlists in the standard WinAmp format, as used by just about everything. Plugins enable you to add features, like listening to Last.fm streams, adding visualisations, displaying the current track on an OSD, or shrinking everything down to an icon in the system tray.
Whether you are using a netbook or just don't want your audio to take over your computer just to play background music, Audacious is an excellent choice of player.