What is the advantages of Iterative model

This model is useful when less manpower is available for software development and release deadlines are tight. It's best suited for in-house product development where it's ensured that the user has something to start with. The main shortcoming of this model is that iteration may never end, and user may have to endlessly wait for final product. Cost estimation is also tedious because it's difficult to relate software development cost with the number of requirements.