These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Is he though? He didn't mean to kill Michael and showed remorse for it. He also protects Janie from a rapist and is shown to love his brother.
Let's not forget he planned a mass killings in LA with a bactereological bomb, burned Archer's best friend alive along some doctors and brutally shot dead his long-time fiancee Sasha with no exitation at all. Obviously he felt some kind remorse for Michael's death (although not totally), but not enough to prevent him to cross the Moral Event Horizon and keep being a blood-thirsthy psychopath he really is.
Ending Fatigue - The climactic battle between Archer and Castor goes on for an insanely long time. Archer's final cry for Castor to "DIIIIIEEEEE!" seems rather on the money.
Fridge Logic: If Troy and Archer have differing blood types and this fact is a plot point in getting Archer's wife to realize Archer is Troy, how come Archer's body didn't reject Troy's face when it was put on him?
Anti-rejection drugs. These days people that get Real Life facial transplants need to take them for basically the rest of their lives.
YMMV, Archer (as Troy) being sent to a super max prison "where the Geneva convention doesn't exist." A few years later, a certain bay in Cuba would have just such a prison.
Hilarious in Hindsight: Any review that slammed the movie on the basis of the "ludicrous" concept of face transplants. Especially the ones that went to great lengths to explain why it's not medically impossible.
Read this. Laugh your ass off. Laugh even more when you learn that at the same time those photos came to light, two more films starring Cage and Travolta were announced.
Moral Event Horizon - Castor burning Archer's friend and partner alive, with everyone who worked on the project.
Before that, Castor did plant a chemical WMD intended to destroy Los Angeles. He was well over the horizon before the movie started.
His accidental killing of Archer's son seems to be his own moral horizon; as he appeared to be genuinely horrified when it happened. Realizing what he did was monstrous, he then just decided to be as evil as possible.
Most of Nic Cage's time as Castor Troy is full of this especially that one face he makes when he grabs the girl's butt.
Tearjerker - When Castor weeps over the body of his beloved baby brother, and lovingly ties his shoelaces for him one last time.
Sean, face restored, comes home. He's already in the arms of his wife. But then we hear "Dad?" from offscreen. The shot changes to Jamie, who is no longer dressed all punky. And her face lights up with joy as she breaks into a top speed run to hug her father. "Dad?" she says. "I'm sorry I shot you." And he just silently shakes his head and gives her the peculiar affectionateFacePalm particular to this movie to show her he forgives her.