The critique on nudge as manipulation probably caused by defining what is desirable behavior. That is the outcome of a political process for which we elect representatives to make decisions representing the preferences of majority. Nudge focuses on implementing the legislation given those political decisions. An interesting example is the healthy eating pyramid. This was a complex figure which did not provide much insight on what people need to do to eat healthy. Nevertheless this pyramid was widely used, especially in schools. The office of Sunstein developed a new way to visualize healthy eating habits with the "choose my plate" visual, which is clearer on what kind of behaviors are expected for a healthy eating habit.
If Sunstein is right, we can expect to see many changes in the way legislation is implemented. Based on insights how people actually make decisions, legislation might become more effective and less costly. Of course, whether this leads to the desired outcomes also depend on the political process which define the desired outcomes.