Was the plumber professional? Was he or she on time? Did they do what they promised? Is their work neat? Do you have hot water? How was their response time? Were they well mannered? Were they clean or dirty? Would you call to have them work in your home again? Did you like them? If the answer to all of the above is yes what does the price really mean?
Umm, you forgot "Did they smell good?
(or are the "smell good plumbers" only known in California?)