You get the full set of features including playlists, radio stations, the For You section and music you might have synced to your library from another source on another device. There are a few things it cant do such as live stream the Beats 1 radio station or present you with smart playlists.
Nevertheless, it is welcome and means that users can finally log in to their music over a desktop or laptop without needing an iPhone or iPad nearby to take advantage of the streaming service. You could now realistically pay for Apple Music without primarily using Apple products.
It shows Apple’s slight hesitancy to go all in on streaming since the iTunes download model was eaten up by the runaway success of Spotify.