Let me start with what I liked from the book: the observation about everyone being a diplomat of his/her country, culture and/or institution, of the fact that NGOs can be more flexible than nation-states, and the acknowledgement that NGOs, corporations and even single people are important political players in todays world. This is the reality and it certainly should be embraced in one way or another.
However, apart from this, the rest 4/5ths of the book is over-optimistic praise of the actions of said players, at the expense of nation-states with some ideas that contradict each other and present the author's shallow understanding of history or economics mixed in with hopes and dreams of some globalist institutions and think-tanks.
Let me start with his metaphor of "the next Renaissance". His comparison of a current world to a medieval one is not really valid. For one, the trade and importance of non-state players did not start in Renaissance, like he claims. In the Antiquity Romans created a tremendous empire based on the flow of goods from one end of Europe to another, and their sophistication of banking, commerce and politics was really impressive (including financial crises as well). It survived during the Middle Ages, especially in Italy. Medieval world was also no more fragmented than Renaissance one, or than it is now. Renaissance did not end indented servitude, slavery, or other woes of the world.
Second, the economy based on credit is seemingly reaching its final capacity. To advocate the fact that bank can issue any amount of credit it wants, just making sure that it is securitized, is a folly which lies at the roots of present financial crisis. If an underwriter of a security does not have enough money to cover the losses if the credit is not paid, then the whole security is worthless and no rating agency is going to change that. The risk does not disappear, just because you think you transferred it to somebody else. This is a major flaw in the thinking that is presented in this book. Considering noticeable trends of some important players to come back to a currency that is in some way asset-based, the author's ideas seem to be a little out-of-sync with reality.
Third, singing the glory of NGOs, corporations and "philanthropists" is unfortunately possible only by picking and choosing from their actions, and is an excellent study for confirmation bias. For every example of good deeds done, there is a counter-example of the harm done either intentionally or not. To present the issue otherwise is a fallacy. To advocate that they would bring the Utopian New World Order if they were not hindered by nation-states, is a folly.
Fourth, some of the recipes to remake the world presented in the second part are really astounding. Advocating assassination of government leaders hardly seems to me as an example of "diplomacy" in any way. It is also very easy to divide countries that are thousands of miles away, because it seems the right thing to do advised by a few selected experts.
After reading the first part it almost looks as if the good ideas (decentralization of power, initiatives that come from bottom-up instead of top-down) were really a bait and switch for presenting another Utopian vision of the world, which is not a result of proposed changes, just a place where the power was transferred to other big players.
All this also suffers from the one-sided look at human nature, without any serious consideration of the dark side - the thirst for power, the love of money, fraud (praising Khaddaffi's Sovereign Fund in the light of recent events in Libya is really a good illustration of author's bias), racial and ethnic hatred, and all other things that also make us human.
Overall the book is shallow, optimistic, and misleading. It might be important to read it to know that there are people who think this way, and who also have important voice in current world of politics, but apart from that - reader beware.