I think the best thing he brings is unpredictability. Most players look for other players to pass to, whereas he usually looks for the space for them to run into, and then passes it there. He plays with his head up, and you can see he's always looking for the opening and something different, and to unsettle and stretch the opposition.
Players like him also encourage others to make those runs and find that space, so its 'win win' having him on board and slotting into Klopp's template so seamlessly.