Kessie is good, just a bit passive and inactive.
When he actually gets on the ball can show some nice ability from time to time but lacks the initiative and urgency when he plays. Pretty decent dribbler and hard to take the ball off but he almost never does it. He seems happy to let the game pass him by a lot.
Could be a stamina issue, that he can't sustain long bursts of intensity.
Xavi recently praised him that he never gets tired.