It needs Internet to connect to its database for recommendations and you need to use the app to play your music, but thats the only way there is. It plays music similar to whichever song Im in the mood for, so I dont need to make a playlist every time I want to listen to music, and it syncs with your last.fm account to save your scrobbles.
fossDAboss about Scrobbler for iOS, v1.3.1