Strengths: First and foremost, his tremendous left foot, especially from mid and long-range. If you give him space, you're done. Very quick in his mind, once he controls the ball, he already knows which teammate he has to pass the ball to. His passes lead to promising attacks if it's not the assist. Once he passes, you can be sure that these are accurate and sharp. Good pace on longer distance. He can take free and corner kicks and also penalties if needed. He controls the ball fairly close on his feet which makes it hard for defenders to steal the ball. Despite being left-footed, he can pass and shoot with his right foot as well. He can play on the right or left wing in a "Tridente". He is not he best team defender but very smart if he does defend, sneaking from behind to steal the ball. Moves inside from the right wing to finish with his left foot. Mature.
Weaknesses: Physical side of his game. Sometimes falls easily (he is not a diver, though!). In some periods of a game you don't get to see much of him. He seems to be shy in his body language, so he needs more determination off the ball. Speaking of his off the ball actions, his zonal marking could (or even should) be a bit better. Needs quicker feet when switching from defence to offence without the ball. Some of his corner kicks didn't impress me.
Conclusion: Growing up at Inter's youth academy, he surely can provide some quality football. There might be a few reasons why he didn't succeed in Serie A yet. Maybe because his game is too predictable at times? Or his coach in Bologna put him in the wrong position? Siligardi has a good vision on the pitch but this doesn't mean automatically that he can play as a playmaker (which in return also doesn't mean that he couldn't, though). There is a reason, why his current coach Davide Nicola uses him as a right winger in a "Tridente" although he is left-footed. It's also difficult for him to play as a striker being not the strongest physically. Livorno is on a good way towards Serie A and we will see how he will adapt there. Serie A is way more physical and tactically challenging than Serie B, of course. But if he is allowed to play in the position he feels comfortable most, I don't see a reason why he shouldn't share the same faith as Alessandro Diamanti who years ago was at the same position as Siligardi, leading Livorno to Serie A and then establishing himself there after a short spell at West Ham United (first with Brescia Calcio then with Bologna where he is still playing).