Some people were disappointed when Amarok 2.0 was released, it had changed a lot from the tried and trusted 1.4 and not to everyone's liking. Amarok 1.4 was still around, but uses the older QT libraries, which modern distros do not install. Being open source, it was almost inevitable that someone would take the Amarok 1.4 source code and begin porting it to QT4. What was far less inevitable was that the porting project would reach the stage of a usable release, but that is exactly what Clementine has done.
Porting to QT4 has two advantages, not only does it mean that Clementine can run on modern distros without needing older libraries, but QT4 is also available for Windows and MacOS X, so Clementine is now truly cross-platform.
If you ever used the older Amarok, you will feel immediately at home with Clementine. Some of the more esoteric features have not made it across (yet) but that's not necessarily a bad thing, Amarok was already beginning to get quite bloated (or feature rich, depending on your point of view) by the 1.4 release. The basics are there, playlist management, ID tag editing and Last.fm integration. The latter not only allows you to listen to music from Last.fm, you need an account there, but it can also download cover art from their site. Clementine can also play streamed audio fro many Internet radio stations, although it doesn't have the podcast support of Amarok 2.
If you want a basic but functional music player that fits in with a KDE desktop, you won't go far wrong with Clementine, even at this early stage of its development.
Clementine 1.0 adds Spotify, Grooveshark and SKY.fm/Digitally Imported support. We've also added a Global Search feature that allows you to easily find music that's either in your library or on the Internet. Other features include audio CD support, more transcoder options, an improved settings dialog, smarter album cover searches, and loads of bug fixes. See the full changelog for more information.