I've been using Haaland as a lone striker in a 4231 whilst playing in Rivals DIV.2
This man is an absolute beast. He is tall, strong, clinical, and fast. He is a tank as a lone striker who shoots rockets with both left and right. He is literally a machine. However, that's all he is and does. He can the most ridiculous overhead kick in the first minute of the game only to miss a two meters pass seconds later.
If you are looking into buying Haaland, you should know that he does what his job is on the pitch. Score goals. He cannot, however, dribble or pass. He feels stiff on the ball as soon as the direction changes from straight forward, do not even think about doing anything other than playing short passes back to a CAM or CM.
However, if used right. He will score a lot of goals. Which is what I was looking for when I brought him into my team. He is extremely dangerous once he has passed the backline and get to use his strength to shield the ball. This man is a target striker that passes the ball back to a CAM before turning on the jets and heading straight towards the goal. And once in, he doesn't miss.