For the most part this episode (mp3) fails to spark an actual debate, certainly not a debate about the so-called new atheism. Melville, the atheist proponent, argues primarily for secularism. He also dismisses Sam Harris as a reactionary Islamophobe before going on to characterize an Islamic upbringing in which one book has all the answers as "a nightmare scenario." Melville also criticizes prominent atheists for being too shrill and blunt, which is just accomodationist drivel. Around 45 minutes in, the Melville and McGrath finally get around to having something resembling a debate, but not about the subject of the new atheism, and even then Melville remphasizes that he is not defending any particular truth.
I'd have preferred a discussion which focused on some particular truth claim and examined the evidence for and against it. Perhaps that happened once or twice in this episode, but only incidentally and in passing.