Objects which are less dependent on other objects for data are likely to be more reusable. If objects are actually being designed to be reusable beyond a single application, then the effects should appear in object library usage statistics. More complex methods are likely to be more difficult to maintain. Greater method complexity is likely to lead to a lower degree of overall application comprehensibility. Greater method complexity is likely to adversely affect application reliability.
More complex methods are likely to be more difficult to test.
One of the goals of object-oriented design is finer granularity. Therefore, each object's behavior should be more easily understood and analyzed. They have defined six metrics for the OO design. It is defined as the sum of the complexities of all methods of a class. The number of methods and the complexity of methods involved is a predictor of how much time and effort is required to develop and maintain the class.