Listen is a not so widely known audio player written in Python and using the GTK toolkit, with an interface similar to the one of Rhythmbox, and including features like a music library, podcasts support, lyrics fetching, Wikipedia integration, and Last.fm song submission.
The interface is divided into several sections for the currently selected action. For example, if you select Current from the actions list, Listen will display all the albums by the currently playing artist, favourite songs and recently played songs by the same artist.
I really missed the option to sort the playlist by song location, but otherwise, it includes mostly all other criterias. You can sort by artist, title, album, bitrate, play count, date, year, genre, track number and so on. I'm not sure what the 'Feeds' sorting option does, since it has no visible column in the playlist.
I liked the Wikipedia integration, the browser offers several basic functionality options, like searching for album, artist or song, opening in an external web browser, but it doesn't include an option to specify what browser you want to use. It also has back and forward buttons.
The Context tab will show favourite albums, songs and last played songs. Listen automatically detects cover images in the currently playing song directory and shows them whenever possible: in the context tab, in the library at the albums section or in the now playing area. It also allows you to search for default or specific names on Amazon.com and Google Images, but the Amazon search currently doesn't work. It works fine for Google Images though. Allowing you to enter a custom search term is useful in case you don't find what you want but you want to put any other cover or image instead of it.
Listen can be customised different ways using the Preferences window. To mention a few settings you can change: splash screen, start minimized, visualisations, OSD (on-screen display).
Populating playlists doesn't seem to be very intuitive. For example, after creating a new playlist and going to Music -> Import Folder, the playlist remains empty. However I could do it by selecting all the songs from the Media Library with CTRL+A and dragging them over the playlist name.
Overall, I found Listen to be pretty nice and rich enough in features, but I missed statistics and the option to sort the playlist by location. Otherwise, it's very nice, with a clean layout, and offers a very good audio experience.