I think MusiCloud is the perfect music player app on the market! You can listen to music offline and the best of all you can edit your music tags. If you dont know how to use it, I recommend using "mp3 juices" on safari. It helps by downloading files quick and easy into a Dropbox so you can access music on Musicloud and download it directly to your phone!
Wixnerr about Musicloud Pro - Music Player For Cloud Platforms., v1.1