Jace, Ingenious Mind-Mage

Oracle Text
+1: Draw a card.
+1: Untap all creatures you control.
−9: Gain control of up to three target creatures.
Card Rulings
9/29/2017 The control-change effect of Jace’s last ability lasts indefinitely. It doesn’t wear off during the cleanup step or when you lose control of Jace.
9/29/2017 In a multiplayer game, if a player leaves the game, all cards that player owns leave as well, and any effects that give the player control of permanents immediately end.
The card draw is just bonus for when you don't need to untap, from my view.