Safety, mobility and environmental sustainability represent three cornerstones when evaluating the effectiveness of an intelligent transportation system. However, very few studies have conducted a holistic performance assessment for a connected vehicle (CV) based application. In this study, an environment-focused CV application, called Eco-Approach and Departure (EAD) application at signalized intersections, is used as an example. Its safety, mobility and environmental sustainability parameters are carefully evaluated through comprehensive simulation analyses over a real-word network. A variety of scenarios have been tested and the impact analysis is conducted from two perspectives: 1) EAD-equipped vehicles vs. non-equipped vehicles; and 2) overall traffic. The results indicate that the benefits of mobility and environmental sustainability show more consistent patterns across different scenario while safety impacts are more scenario-dependent.