Icardi can be a frustrating card to get used to, but when you find his strengths he turns into a really solid option. I first tried Icardi alone up top in a 4-2-3-1, with Mertens and 1st IF Insigne at the two CAM positions behind him. He was very frustrating to play with; his strength was poor, ball control sloppy, and his passes were just not strong enough to get through tight windows without being intercepted. After about 5 games (3 goals, 2 of them headers), I switched formations, playing him alongside Higuain in a 4-1-2-2 (narrow), with 1st IF Insigne behind. OH MY, what a change that made. In 5 games he scored 11 goals and assisted 4 more. I found the key to this card was to play a strong physical card next to him, to allow him to make cute runs into the box behind defenders. Once in the box, he was magical. I used Hunter, Get In Behind Instruction.
In the Box Finishing: In the box he is one of the best I've used. I'll put him right up there with Harry Kane on finishing in the box. Both feet are strong inside the box.
Short Passing: Works especially well with a stronger striker next to him.
Heading: The go-to target on corners and set-pieces.
Strength: His strength of "78" felt more like "55-60". He was pushed off the ball easily, especially in a single striker formation. Needs someone else to do physical dirty work for him.
Long-Passing: Don't expect to thread cute balls through to fellow pacey wingers, he is weak in this area.
Long Shots: Outside the box, forget about it, gets saved 80% of the time.
Ball Control: Fairly poor first touches and skills. Use him more as a poacher in game.