The Ubuntu Linux cllient for Spotify is very stable and mature. I am using it right now with Ubuntu 13.04 64 bit Raring Ringtail GNU/Linux. Naturally, I have high quality streaming checked on. I find that Spotify sounds excellent on my high end audio system and my large private MP3 library sounds slightly less inferior to Vorbis 320 Kbps bit rate. I chose Spotify because they at least have a Linux desktop client available in beta preview whereas others do not. Music is very important to me as it is for most of us in this community and I was getting tired of my large 20,000+ MP3 library. I wanted new music recommendations from friends that I follow and who follow me back and I also wanted a streaming radio service built-in without paying a separate subscription monthly fee for the privilege. Spotify continues to impress me with their large and deep and expansive music catalog. Everything that I want to listen to is available from Spotify.
The classical and opera selection is particularly good among the other music streaming services that I've tried in the past including Sirius XM Satellite Radio and Pandora and Slacker Radio. I have a Hewlett Packard EliteBook 8770w series with Microsoft Windows 8 Pro 64 bit for my job at work. I've been playing around with Rdio and Vdio along with Netflix and Hulu Plus and other music and video streaming services and I settled upon Spotify for music streaming and Netflix and Hulu Plus for tv shows and movies. Spotify is a clear leader in the industry with a much larger music catalog which makes it feel more complete. It also permits friends to follow one another and share or recommend songs with one another which is a bonus. The streaming radio feature is not quite up to par with Pandora, but it's sufficient for background music when working on a PC for a couple of hours.
To my ears, I find Spotify to be the highest fidelity but not necessarily full spectrum fidelity. It's the least worst sounding music streaming service. The others sound noticeably more compressed or the continuousness of the music stream is intermittent. Spotify with Vorbis 320 Kbps sounds closest to the original loss less music format to my ears. I use the Etymotic ER-4PT/S combination so I know I'm getting dead neutral accurate sound. I also have the Meridian 800v5 and HeadRoom Desktop Ultra with DPS and Monster AV UPS power station.
I find that purchasing and downloading music to be passe just like buying music CDs at the record store. Streaming music and video content over the Internet is the way to go. It costs much less money over the long run compared to building up a private media library and the content is always refreshed every day or week with new content. I find myself less inclined to keep purchasing music and tv shows and movies or e-books a la carte which can be quite expensive.
Spotify is the way to go. I shared my Spotify Premium account with my father and my best friend and we can listen to Spotify and receive personalized music recommendations while logged in simultaneously on our desktop, laptop, tablet, and smart phones across Microsoft Windows, Apple Macintosh OS X, Google Android, iOS, and GNU/Linux. This has been a real savings in terms of cost as I pay a flat $9.99 bucks monthly and I get to share Spotify Premium with family and friends.