Kiefer ,we can say, lives in his father's shadow. He never really got as big movie roles as Donald. Kiefer's movie career consists of mostly B grade movies. Of course there are some expectations, and in these, he does well.
What changed his career forever was 24, in 2001 which also killed it - after 24, I doubt he'll be able to play anything other than Jack Bauer.
His performance on the show is great. He's an amazing modern day action hero. He's just natural with holding a guy, screaming. Which leads me to his voice, which is super awesome. If anything, he can always be an A-grade voice actor. The only issue with his performance in my opinion is the romantic performance. It's random - sometimes very convincing, but other times, it's lacking. However, I think this is mostly due to his character. In the earlier seasons of 24, he was really good at displaying emotions, but lately, his character's been degraded to the level of a robot, making his acting suffer.
Overall, one of the best male action heroes on tv and cinema, but not quite perfect.