There’s an interesting new feature in watchOS 2. In the Music app, the Quick Play button lets you play a random selection of music from Apple Music’s For You recommendations. It will sometimes play an album, sometimes a playlist. If you don’t like what it starts playing, go back to the menu and tap Quick Play again.
If you don’t have an Apple Music subscription, I have a feeling that it plays music on your iPhone in Shuffle All mode. If anyone can test this, do let me know what happens in the comments below. (I can’t test it, because, alas, I do have an Apple Music subscription.)