The most important feature is that it allows you to create your own rules for processing personal data which makes life easier when compared with other software available in market at this time (ePrivacy etc.). I would like there were some better documentation as well - not very intuitive interface but maybe they will improve over next few months after launch? We are using GPMS mainly because we need easy way how organize our processes related information about customer's rights while still keeping up all legal obligations regarding EU regulations such us GeneralData Protection Regulation or eDrektionsverordnungen from Germany so far).