I picked it up today, and I am loving it. 2KGames, and Cambridge Studios did a great job in presenting this game. It lives up to the shows, and it feels like you are watching the tv show, but also controlling it at the same time. The camera, and gameplay isn't that bad as a lot of people are saying. The music, and presentation is straight out of the tv show.
You get to play as Michelle, Tony, Kim, Chase and Jack at least so far from what I've played. I am currenty playing through hour 7. On a scale of 1-10 I would give this game a 8, it is worthy of a purchase if you are a 24 fan or just looking for a new action game. If you aren't a 24 fan I would consider renting it first before you decide. However if you aren't a 24 fan or have never watched the show I suggest you go watch it. It will help a lot if you watched Season 1, and 2 before playing this game since it ties in the gap between Season 2 and 3.
The game doesn't follow the real time format, so the game doesn't take 24 hours to complete. I would ballpark the game to be about 12-15 hours of gameplay. However there is a grading system for each mission (grades are based on how much health you used, how many head shots, how many civilans that were saved etc), and the grading system might draw you back if you want to achieve a perfect grade for each mission.