Written using GTK# and Mono, Banshee is currently only at version 0.10.4, but I've found it suitable for my everyday use and haven't encountered any stability issues at all.
Ease of installation varies across Linux distributions, but the project's Web site provides good documentation. The popularity of the project is increasing, and as a result the latest version of openSUSE has Banshee as a default music player. Installing Banshee will be easier on some distributions as Mono becomes a standard; until then, the instructions on the site should be sufficient.
Starting the application opens the Import Music window, which offers two options for importing your music: manual or automatic. Once the import process completes, you can play your music hassle-free.
The user interface feels right at home on the GNOME desktop (see Figure 1); the player integrates beautifully, with a tray icon that enables you to perform functions such as pausing and switching between tracks and hiding the player. The intuitive interface makes it easy to get to the program's functions. Writing CDs is a breeze with a button located at the upper right of the main window, which you can see by clicking here.
Banshee is perfect for managing your entire music collection, and particularly items stored on iPod music players (see Figure below). The software allows you to carry out many tasks in ways similar to Apple's iTunes, including playing music directly from the device and creating playlists with your songs. Banshee supports a wide variety of codecs, including Ogg Vorbis, FLAC, and MP3. The player read ID3 tags perfectly for my music collection, and sorting through the tracks -- comprising several file formats -- was incredibly easy.
If you have an enormous music collection, you'll appreciate the search bar, which can filter searches by song name, artist name, or album title. I love the Fullscreen option, which runs the application in a full window, covering the GNOME panels and removing the window borders.
Banshee's plugin architecture is fantastic, allowing external developers to add even more functionality to the application. One plugin worth mentioning is the Audioscrobbler plugin, which allows users to build up a profile of their musical tastes by using the popular online service.
My only annoyance with the player is with the excessively large amount of blank space at the top of the window; when right-clicked, this area provides a menu that displays useless options such as "copy" and "paste," which are grayed out.
I've found Banshee to be a thoroughly satisfying player. Your requirements for a music player may differ from mine, but give Banshee a shot.