What I was most intrigued to learn about the Showtime series was that, according to the show's website, the makers of This American Life - the radio show - were unwilling to make the transition to television at first. What finally convinced them, was that they thought it would be challenging and fun. I applaud them for creating such an intriguing and well-produced show, especially since they had never made a television show before.
The show's roots in radio are present in the episodes, which is what I think makes the show a success. Whereas in another project, narration would be hackneyed and troublesome, Ira Glass carries it off with ease. I think this narration is what makes the show so concise. Each episode follows usually three stories and for a half hour show, the stories could easily be glossed over. Each story, however, is expertly explored. The narration helps tell these stories in an economic fashion and ties them all together, fully explaining the themes of each episode. The fact that the show stems from a radio show is apparent in its style and allows for usual television cliches to be reborn and innovative.