An impressive achievement, very informative and thought-provoking. Ober really argues from everywhere, the book is a tour de force of political knowledge. But Ober's goal was extremely difficult to attain, and I believe he fails to do so. In fact, after all the work Ober is forced to put in, I think I've become more aware of how much of democracy's appeal rests on its modern intertwinement with liberalism.
Regarding the arguments, I have some general issues with Ober's use of positive theory, specifically with his (optimistic) scenarios of social equilibrium (the only guarantees of liberties and rights). But my main contention regards his defense of democracy as the only way for people to exercise certain inherently human capacities. The whole argument of the book depends on this holding up. But Ober doesn't explain why deliberation and collective reasoning and decision-making at levels other than the state (say, a company) aren't sufficient to exercise such capacities and to produce the so-called "democratic goods".
Another issue that is hard to look away from is the fact that, in Ober's basic democracy, status inequality (say, a cast system) is acceptable as long as, as citizens, people are equal. This allows Ober to make his basic democracy fit with iliberal regimes, but it's a bit wild.
One final thing I struggled with is Ober's insistence on referenda. I am sympathetic to his arguments for a more deliberative and participative form of democracy, but I think he is being quite unrealistic about the possibility of implementation and actual success of what he calls civic education.
Despite all these misgivings, Demopolis is definitely a good and original book, with many valuable sections that can be read independently (e.g. the part on democracy and expertise). Surely a must read for those interested in political theory.