Below are listed three main benefits from Agile that help the Project Manager to execute the belly dance between the various constraints in the IT projects:
- value added to customer - Hard to explain and even harder to sustain in the initial stages of waterfall. In Agile instead, everything is customer-oriented: flexibility to changes, business orientation and attention to user feedback.
- risk management is less painful with Agile because of iterations, prototyping and user feedback that allows spotting risks and errors early.
- coping with uncertainity - and this is my favorite. Never seen the IT project where the contract is perfect, scope is definitive and without grey areas and the technical solution is clear. Agile has concepts created by people that understand things are usually less then perfect: Moscow list, prototype, fail-early, collaboration with the client and mixed teams.
Here is a nice comparison of Agile vs waterfall: