Up until now all I did was read wikipedia's summaries on Live Another Day because I didn't like Seasons 7 and 8 as much. However, I watched the final when it came on last night. (Contains spoilers of course)
The good: Cheng's dead. Jack finally got his revenge for torturing him for over a year, torturing Audrey, and, as of the final episode, killing her. I imagine this will be second only to, or even surpass, Nina Myers in "Top 10 Jack Bauer kills". This has extra power in a year where shows rarely kill off villains anymore, seeing as how he appeared in three earlier seasons of 24.
The bad: No Mandy, I was hoping she'd return, maybe as Cheng's sniper, but it was a male Chinese sniper. They lied when they said Mandy could return. Also, at this point I didn't expect Tony to return for redemption, if he was going to it wouldn't be in a final episode. And, once again, they end it bad for Jack, he is imprisoned in Moscow by the Russians.
At this point I'm not sure whether to accept Seasons 7 and above due to Cheng's death or ignore them due to the things with Tony and Jack