Biddle et al observed many teams, whose members have different background, to tackle the same design exercise. This gives them opportunity to observe the effectiveness of the CRC cards, and reflect on the strengths and weakness.
After observation, they claim the CRC card technique has 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 facilitate open discussion of dynamic structure, the "what-if" exploration, by use of object roleplay
In the detail discussion of the three strengths above, based on their experience, they also states the weakness of CRC card technique and strategies they come up with to address these weakness.