Since Hans never accomplished his goal, we cannot be 100% certain of whether or not we would be a despotic ruler. But judging by the fact he betrayed Anna and almost killed Elsa to gain the throne, I think it's safe to say that if he was willing to use underhanded means to attain his goal, he probably would rule with an iron fist.
I am sure that the only reason Hans wanted to become king was
well. . . To become king, I don't think he would have forced residents to work or ruined their (already) ruined economy. In my opinion, he's a better leader than Elsa or Anna, who locked themselves up, while Hans (when Anna let Hans rule when she set off to find Elsa) actually helped the citizens firsthand instead of making the officials do it, like Elsa and did.
Look, he is a huge jerk for lying to Anna ( heck, why did he even need to tell her ?) but in his eyes, he's killing Elsa, and saving a kingdom. By the way, he wouldn't be a tyrant. He's just jealous of his brothers. . . . .