'My Chill Mix' starts getting pushed out to some Apple Music users2
Each subscriber's Chill Mix will update once a week, apparently every Sunday. A pair of control buttons will allow the subscriber to play his/her Chill Mix in the order seen on the screen, or the titles can be shuffled allowing for a random playback order. Each Apple Music subscriber will end up with a unique experience based on his/her listening habits.
The "For You" section that will host 'My Chill Mix' when you receive it, is also home to other features such as 'My New Music Mix' and 'My Favorites Mix.' The former is a curated playlist of new music that fits the style that you normally listen to. The latter is a list of songs that not only is based on the kind of music you listen to, it also includes music that you've already noted as being among your favorite tunes.
source: TheLoop via AppleInsider