Paraphrasing Abraham Lincoln, I'd say that Zizek's excerpts have some good new ideas, but the ones that are new aren't good, and the ones that are good aren't new.
First the "good" ideas: Is Zizek unfamiliar with the Marxist-Christian dialogues of the late 1960s and early 1970s? Or does he think we all have forgotten them? Not to mention Brazilian liberation theology and Sandinismo. How do Zizek's observations differ from those, except that his are so superficial in comparison? But besides the points that are obvious to the point of banality, if one wishes to honor the revolutionary origins of every great religion, and to record their subsequent degeneration to today's reactionary remnants, why choose Christianity in particular to mention, except to pander to a handy constituency that may not merit such esteem?
As for the "new" ideas -- surrounding Marx's alleged mistake that he claims to correct -- Zizek's abandonment of communism both as a goal of anti-capitalist struggle and as a standard by which to measure success, is a transparent, not to say disgraceful, grab for academic legitimacy, exactly what one has seen from nearly every ex-Marxist celebrity, and fully to have been expected. All that is new here, if anything, is his choice of quibble.
Ken Lawrence