Based on Biddle et al’s paper [2], CRC cards have three basic strengths:
CRC cards facilitate open discussion of static structure of a system.
CRC cards have built-in heuristics that guide design, in the nature of determining the Class Name, the Responsibilities, and the Collaborators.
CRC cards facilities open discussion of dynamic structure, the "what-if" exploration, by use of object role-play.
However, like nature, everything has dark side. Therefore, there are also some weaknesses of CRC cards.