Rawls's work is quite bad. His style is boring and awkward. He writes in half-retractions. He offers a method but doesn't stick to it. He advances principles but doesn't really argue for them. (For instance, his argument for moral powers test of basic liberty is radically incomplete--he offers hardly any reason to believe it, and he offers even less reason to think it picks out the liberties he favors.) He largely ignores critics. He straw mans the views he criticizes. He offers criticisms of others but ignores whether his criticisms apply to his own work. His argument for his most famous idea--the difference principle--is clearly unsound, as Wolff demonstrates here.
I suspect it's because he gave himself an absurd task.
Rawls often said that he was trying to articulate and defend the implicit, substantive theory of justice inside the culture of the modern democratic nation state.
Here, then, are somewhat snotty but nevertheless accurate summaries of his two biggest books. A Theory of Justice: Idealized agents under a veil of ignorance but who possess special knowledge of sociology and economics would unanimously choose...wait for it...something like the 1972 Democratic Party Platform. Political Liberalism: All reasonable people committed to a free and equal society, but who recognize and respect diversity of value would...wait for it...end up agreeing with Rawls that we should implement either the 1972 Democratic Party Platform or the 1972 Social Democratic Party of Germany's platform.
Here's the problem, then: Consider the big political parties--the ones that actually get into power and rule in modern democratic nation-states. (You can ignore fringe parties like the communists, libertarians, etc., here.) The platforms that these political parties have--not merely their particular platform in any given year, but their overall tendencies towards various policies--are not derived from philosophical principles combined with economics. Rather, most political parties are composed of a wide range of interest groups with very different ideologies, and often no ideologies at all. These different groups have different goals with differing strengths. The platforms that emerge in any party are half compromise and half accident. Parties push incompatible ideas at the same time and in the same breath.
The platform of any big party is a hodgepodge of largely incompatible ideas or ideas in deep tension with each other. These tensions arise in part because the party is trying to please different people with conflicting goals and interest. These arise because their voters are usually uninformed, irrational, and inconsistent themselves. They arise because parties mostly want to do what sounds good but also sometimes want to do what is good. They arise because most people are confused and unprincipled themselves. Any given member of parliament probably has inconsistent ideas and goals. The body as a whole does too.
This holds not merely for any one party, but for the overall politics that emerge in any particular country.
You cannot produce a good, simple, principled, but very substantive account of the implicit theory of justice underlying a modern democratic nation-state because the principled part is rather minimal. My point is not to say that because people disagree, there is no truth in politics, and no substantive theory of justice is correct. Rather, my point is that Rawls was trying to provide a principled defense of what he regarded as the rather substantive implicit principles of justice in modern democratic nation states. But modern democratic nations states have no such implicit robust theory; all they have is something far more minimal.