To play your music on 'streaming, you'll obviously need an internet connection, whether it’s WiFi or 3G. If you choose to download your songs onto your device then you’ll be able to hear them without an internet connection. This can be very useful for users with a limited 3G connection, or any other limited connection.
The application also lets you keep your music in the background, and even lets you control it from your lock screen, a very useful feature for users who usually do other things while they listen to music.
Amazon MP3 is a must-have application for any user with an Amazon MP3 online music store account.