Jet is an interesting character, because of his "Clockwork Orange" type development.

In Book 1, he does come across as a calculating, dangerous person. Everyone becomes turned off to Jet when he indiscriminately decides to massacre a village, just because Fire Nation soldiers are there as well. His Peter Pan/Robin Hood charm wore off very soon after he made this decision.

Not to mention that in Book 2, he maliciously tries to undermine and expose Zuko and Iroh, even after they've turned over a new leaf in Ba Sing Se. It doesn't really help Jet's case that he assaults Zuko in the tea shop, and tries to egg Zuko to use bending to defend himself. Jet was clearly painted as an anti-hero by this point in the series. Maybe he has his reasons, but it wasn't exactly justifiable.

However, when he becomes brainwashed by the Dai Li, our opinion of Jet changes. When we meet him again, he's mostly docile and even uncharacteristically submissive. He even wants to help the Aang Gang, though no one really trusts him. So, it leaves the audience to question: Is Jet better off free-thinking and dangerous? Or, is he better off with this new outlook on life, even if he got here through brainwashing and dystopian manipulation?

Jet does manage a bit of redemption at the end of "Lake Laogi," and it feels earned. Watching Jet lose control of his mind and his body to attack Aang was thrilling and devastating in equal fashion. The show got rid of Jet at the right time, and he still managed to earn a hero's death.

It's a tricky game that ATLA pulls off with Jet. I think it's better that the show didn't bring much attention to this subplot.