In the first Radiolab episode, "Darkode", hosts Robert Krulwich and Jad Abumrad tell entertaining stories that are based on hacking, from a remote hacking of Inna Simone, to a highly optimized and well funded organization of hackers in Europe called Darkode (stylized as dark0de), where the episode gets its name from.
Right off the bat, the hosts pose a rhetorical question that grabs the listener's attention, which gives the audience something to think about while the guests tell their story. The producers waste no time in putting in distinct soundbites that keep the listener on their feet. Throughout the episode, sound effects are used even more effectively to mirror and augment the natural emotional reactions to fluctuations and climaxes within the story, for example intense music when the story comes to a particularly exciting moment or silly music when someone says something funny.
In addition, the way that the episode was edited made the conversation flow better, but I'm not sure if it seemed more natural. Different parts of the conversation were spliced together so that there were almost no pauses between when people spoke, and although this started to stray away from the cadence of natural conversation, it somehow made the episode flow better. This made the episode both more interesting and more accessible, because the conversation was more engaging and never got boring.
Also, the format of the episode in which several "sub-episodes" were put into one big episode was interesting. It certainly didn't drag on in the same way that shorter episodes dedicated solely to one topic tend to be, and even though the episode was very long, it didn't get boring to listen to.