The Uruguay international has praised the attacker's positive attitude, and feels the former Real Madrid forward will only become more important
Cassano has developed into an important first team member since he joined the Nerazzurri from AC Milan in the summer transfer window and Gargano feels there's much more to come from the flamboyant forward.
"He's such a crazy joker, he never shuts up... But it's great to have someone like that in the team," Gargano stated to Sky Sport 24.
"Have I been surprised by how well he's done? No, I'd played against him before so I know how good he is.
"He still needs to reach his best form - he's said as much himself. The time will come when he can play every game. I hope he gets back to his best soon."
Cassano has netted three goals in five Serie A appearances for Inter this term.