Wikipedia says Jack killed 39 people in this season, roughly the average of all seasons. Of course I wanted Audrey to live, but Kiefer Sutherland understands that not every story gets a happy ending. As always, I found myself wondering how he stayed alive, so yes, his performance was as good as ever.
I have heard some people argue that they expected a happily-ever-after for Jack and Audrey, but honestly they haven't been paying attention to previous seasons. Watching Jack Bauer after Audrey died was brutal, but absolutely brilliant television and Kiefer Sutherland deserves serious recognition this time around. The only real question we're left with is how functional Jack will be if things carry on the way they are.
It was classic Jack Bauer. He had to go and save the day and leave the woman he loved at risk. He tried to save her but later learned of her demise and still ended up getting revenge and saving the world once more. They didn't try to remake the wheel and stuck with what they knew and it turned out great.
I was a fan of 24 for many years. The complex, yet similar, story line where Jack Bauer always saves the day captured me. However, I found the storyline grew stale and rather than making it more engaging, the violence and shock factors were turned up to the point of fantasy. It no longer could be believable.
I had such high hopes for the series, and I think most of us did, that it would have been almost impossible to meet them. I think that this is the case with most season finales or series finales because we have as a viewing public invested so much in them.