---Spoilers for 24 Season 6 contained within---
OK. Now that it's over, I will say that this was the worst season of 24.
I'd say that the best parts were undeniably the beginning and the end, especially the first four episodes and the last two (the finale). They pulled a last-minute save on the Vice President and basically broke him, taking him from stupidly evil to ridden with doubt and regret. I still don't think he's a good character but they at least did
something with him.
The end, with Jack confronting Heller, is great and deeply moving, throwing into doubt whether Jack really has
anything -- anything at all -- left. They even silent clocked him, and to anyone who hasn't been paying as much attention, this is only done to characters who are dead or about to die. Scary, and Sutherland's acting was %100 convincing throughout. I never actually thought I'd be worried that Jack Bauer might kill himself.

Scenes like Josh shooting his own damn grandfather upped the tension and, in my opinion, the finale and first four episodes rank up there with the best of 24, with some devastating moments.
The rest of the season? Well. It kinda sputtered out in the middle. Not much happened that we hadn't seen before until about the death of Fayed, characters remained largely static and caricatured and Jack was taken out of the picture. They turned it around eventually, but there's just a large block of sub-par episodes that leaves a slightly bad taste in my mouth.
I liked the new CTU staff a lot better at the end of the season than I did at the start. Maybe everyone's personality is better after 24 hours awake or maybe the writers realized they didn't have very complex, interesting relationships, but they sorted it out and I wouldn't mind another season with this set -- as long as the writing was as good as the last few episodes.

Bill Buchanan became a likeably kickass character, while Nadia Yassir became conflicted but strong-headed. Mike Doyle went from over-the-top racist to Agent-not-quite-as-good-as-Jack (who has problems following orders with which he disagrees).
Chloe, Morris, meh. They are no longer bad characters but with the whole pregnancy angle it seems like they should write them out of 24 and move on. (Please, no more babies in the office. Please?) Tom Lennox, like a lot of the characters, went from caricatured to interesting over the course of the show. One complaint with the White House staff is that, well... Wayne Palmer didn't do much. He's a good successor to his brother but not nearly as charismatic and looking back on it I like the decision to send him into a coma.
Overall, I'd give this season a 7.5, the lowest of the 24 seasons. But it leaves the door open for better things in the future.
Any other thoughts?