There are so many better choice for Music downloader.
You can try Zing MP3 with huge music, video database and music download functionality (it's free absolutly but Vietnamese Interface):
https://itunes.apple.com/us/app/zing-mp3/id457008165?mt=8
If you want video/music/document downloader. I recommend kADM app:
Free version: https://itunes.apple.com/us/app/automatic-download-manager/id680469521?mt=8
Paid version (1.99$): https://itunes.apple.com/us/app/automatic-download-manager/id665831918?mt=8
Easy for using and powerful. You can download video, music, document from all site (except Youtube because app with this function shall be rejected by Apple)