He scored 4 goals in 30 Azzurrini U-21/Olympics matches, of which one is a freekick, one is a ehhh I don't know how to describe it, but clearly Dessena was there and might have touched the ball as well, anyway Dessena's existence influenced the goalkeeper's decision, one is a shot from the edge of the penalty area but rebounced the ground which again influenced the goalkeeper's decision and another one is the famous shot in the Honduras game (Olympics). So only two goals were actually good ones.
The thing is his biggest problem is not his shooting skill, IMHO, which is not that bad, rather he hardly got himself in a scoring position or the opportunities to score, even if in the matches he played as a SS. In one match, he usually got zero to two chances to score and 95% of these two opportunities were from outside of the penalty area but his long shot just lacks strength. He played as SS in the match against Lecce and the second match against Bate (0-0 in which he lost a penalty), I don't even recall him shooting in that two matches playing as SS (maybe some tempted shots blocked far too easily by defenders). Inside of the box is just not his area for some reasons (perhaps due to lack to strength also because of poor running of the ball).
Overall, for a midfielder he's weak in controlling the ball to guarantee the fluid of the match and for a striker his scoring rate is below average of a good second striker.
PS: He had a decent season in Empoli but by watching a few Empoli games, one noted that it was totally different playing attacking position for a team that defended with 10 men for about 80 minutes of a 90-minute match. Their opponent attacked and attacked (because most of the teams were stronger than Empoli) and left a lot of space up front and Giovnco was not marked as someone special so he had much more spece than in Juve.