Also, I was thinking about why I fell for this show so hard and so fast, and I think I have some ideas, although they may tell you more about me than about the show.
1) The show is an amazing balance between genres (buddy cop drama/period piece/surreal scifi-fantasy), has a stunning couple of actors to pull it off (well, the entire ensemble is good, but the chemistry between Glenister and Simm really sells the conflict), and is extremely well-written and well-made. That is all stuff I am consciously (and subconsciously) aware of when I watch a new show, so this explains some of my attraction.
2) I could not get over John Simm's performance as Sam Tyler when I first watched this. Now that I've rewatched the first couple of episodes, I'm able to put words to what grabbed me: it's the little moments. The scene in the pilot where he's driving the car and upset about Maya, but there's no words, and just this quiet, subtle frustration and panic and tears which he tries not to cry. When he's sitting in the squad room back in 1973, and has his arms wrapped around himself, and his gaze is anywhere but present. Later in that same episode, Sam's sitting in the canteen trying to compose himself, and he doesn't seem to know what to do with his hands: touching his face, acting like he's going to fold his hands on the table in front of him and then no, for some reason he doesn't want to do that, and just seeming very confused and uncertain.
Which leads me to 3) because this, the little moments, the things that tell us how human the character is and bind us to him, is what I do in my writing. I love writing fic because I get to write the quiet moments in-between. Life on Mars is a great cop drama, scifi show, '70's set piece, but what it is most of all is a character study (of Sam Tyler, but of all the other characters as well, as we get deeper into the stories). And I love it for the same reason I love, say, The Dead Zone.
Um...in other news, my brain attempted to cross over Life on Mars with Blakes 7 today. No, I don't know. I really don't.