I've watched the first 4 hours in the new season of 24 and it was fun in a guilty-pleasure way. I started watching the previous season, but I lost interest part way through. Having a larger chunk at the beginning may help draw me in more, but we'll see if I stick with it. One of the fascinating things about the show is the premise that everything happens in real time and that combined with an ongoing cliffhanger structure can make for interesting television. The fast pacing makes you forget about some of the more implausable elements as you're watching for the next surprise and trying to figure out what twists lay ahead.
Stylistically I like the way it's shot, just enough shaky hand-held and split-screen to keep it interesting and not nauseating. The cross-cutting, running, car chases, and parallel stories don't allow a lot of depth or character development, but it keeps you guessing and has kept me watching. Sometimes you watch things to become emotionally involved and learn more about the human condition such as Six Feet Under, other times you want to be entertained and it's been a while since I've watched more than one episode of a network drama.
The interesting question about 24 is how many more times can they do it? Will it move to policy issues? "We can't get this budget balanced!" "Wait, the formula in that cell is wrong, Excel won't add it up correctly! Don't hit enter! Noooo!"
Another part of the enjoyment is seeing how the writers paint themselves into corners and get out, maybe it can go on for a bit longer. The world is a scary place and action shows that pull in some frightening current events and images with a hero trying to save the day may use the momentum of the news to provide a bit of a diversion.