Ease of use is related to localization. Translation and overwrite sentences are required for non English speaker as an additional work. If you have multi language option, that would be great.
Net Promoter Score is a loyalty metric used as a KPI for customer experience, measured on a scale of -100 to +100.
To calculate the NPS, we first ask customers to answer the question "How likely is it that you would recommend this company to a friend or colleague?" on a scale of 0 - 10.
Customers who answer 0 - 6 are Detractors, 7 - 8 are Passives and 9 - 10 are Promoters. The NPS is the sum of % of Promoters - % Detractors.