I think most people who study causal inference would say that Pearl's writing is seldom as clear as a person unfamiliar with his ideas would like it to be. These days, I suspect most people would benefit from starting with Morgan and Winship instead: https://www.amazon.com/Counterfactuals-Causal-Inference-Prin...

In addition to presenting Pearl's ideas more clearly than Pearl himself tends to do, Morgan and Winship also describe Rubin's work more fairly than Pearl does. (On the other hand, Rubin also tends to disparage Pearl's work more than is necessary.)