Don't buy into the hype surrounding this show. There's nothing original or interesting about it. The only thing that intrigued me was the real time gimmick, but after a few episodes you realize that the show could just as easily not be in real time for all the difference it makes.
The things that CTU does to get information and find people are repulsive. If real law enforcement agencies were to employ the torturous tactics utilized by the characters on the show whenever some crisis arose, we'd all be in trouble. Apparently it's perfectly legal to abduct people that might be involved in terrorism and torture them. It would be one thing if the show demonstrated the horror of such tactics, but these methods are glorified because it's Jack Bauer who does them. The same idiots who think Jack Bauer is their hero are the ones who belly-ache if they hear about the terrorists in Guantanamo Bay not getting soft enough pillows for their cells.
Another problem with this show is the way characters constantly relay information to each other that we, the audience, are already aware of. A clever writer could imply a relay of information between characters (for example, when one characters begins to tell another character about something that we already know, cut to something else). But "24" doesn't have clever writers, so what we're stuck with is a bulk of each episode devoted solely to unnecessary exposition.
It also seems like the writers tend to resurrect one-shot characters from previous seasons just because they want another familiar face to show up in the new season. Perfect examples are Sherry Palmer and Kim Bauer. The only purpose Kim had in the first season was to be kidnapped and serve as the bad guy's bargaining chip against Jack. After season 1, her purpose was over. The writers should have written her out and explained that she was going to college. But Elisha Cuthbert was apparently too good-looking to be excluded from the second season, and as a result we have an uninteresting and unrelated sub-plot involving Kim Bauer getting chased by an abusive father and a mountain lion.
And another thing: what's with the robotic, wooden acting? This show is so busy being suspenseful that it forgot to inject a little humanity into it. Real people don't stand around and scowl, or constantly act serious about everything and only say things that have to do with work. This show needs a little humor -- nothing over the top, just maybe have a character make a wise crack every now and then or even (*gasp*) smile. So far, the only actor who isn't so caught up in the ridiculously contrived tension that he forgets to chuckle or make dry comments is Xander Berkeley, a wonderful character actor whose very human character George Mason is my favorite.
Bottom line, the show is badly written and poorly acted. The real time gimmick is the only thing that differentiates this from any number of soap operatic TV dramas, and even that doesn't hold up after a matter of episodes. Don't buy into the hype -- avoid at all costs.