Recs.
Updated
SpecsUpdate
Pros
Pro Huge collection of music and fast access to newly released songs
Spotify has over 20 million songs and arguably the largest collection out of its competitors and usually has the fastest access to new music.
The Spotify desktop client allows local music files to be imported with the option of syncing with a mobile device which largely mitigates the issue of missing artists.
Pro Supports offline playback
Unlike most other streaming media services Spotify supports playback while offline. Spotify enables premium users to mark a playlist to be available offline on their desktop of mobile clients. This allows Spotify to act as a users primary media player even when no internet connection is available.
Pro Client's functionality can be extended via third-party apps
Spotify desktop client allows for third-party apps. They extend the functionality of Spotify and many of them offer new ways of discovering music. Noteworthy apps include Moodagent, Last.fm, Swarm.fm, ShareMyPlaylists, The Hype Machine, We Are Hunted, Shuffler.fm.