I can’t say much good about Styr. He resents having to share command with Jarl, who has more experience raiding than he does, whereas he’s “a ruler, not a raider”, because Jarl is much younger and has fewer men. Mance chose him for the mission because he brought a lot of disciplined men, which is rare and valuable in wildling culture, but that seems to be more of a Thenn trait than Styr’s command style. According to Jon, he visits harsh punishments on people even tangentially involved in treason, and keeps wanting to hurt/kill Jon despite Mance pointing out he’s useful as an informant. Even though he knew surprise was gone, he chose to burn Mole’s Town and, Jon suspects, let the wildlings stop there for “a bit of rape and plunder”, so he’s not even disciplined; there was no need to burn the town, and in fact just gave the defenders more people to man the Wall with when they could’ve just let them be, and maybe fought them later if they had to. Then there’s his last moments, stopping to survey the destruction instead of leading his men over the barricade, even taking off his helmet despite knowing the Watch has many archers who could take a shot at him. Basically, I’d be a rotten commander, but Styr makes so many mistakes due to his ego and cruelty that even I know he’s no good.