Any answer to this question will be nuanced. It all depends on what your perspective is.
If you think that freedom from humans is the most important point, then no matter how bad the situation becomes, you will believe that your situation is better. Many of the animals in the farm would fall into this category. So, their dreams are not shattered at all.
If your perspective is all about material benefit, then you will conclude that the revolution started off with great promise, but it did not deliver. Life under Mr. Jones was better. Moreover, you would point to the corruption of Napoleon and his reign of terror.
If you take it from the perspective of someone like Boxer, who always says that "I must work harder," and "Napoleon is always right," then your blindness will not be able to see the hardships. Why? The rhetoric of Squealer mesmerizes. All of this begs the question - if you think you are happy, are you, then, happy?
In the end, not all dreams were dashed. Some animals were manipulated, others believed the revolution was worth it, and still other did see the evils.