I wouldn’t say Agile Project Management is more successful than Waterfall Project Management. They’re both good methodologies which sometimes even work well together.
What is successful is not the methodology per se but the Team who applies it and what they accomplish. How much value they deliver for the business is the ultimate measure of their success.
Having said that, key success factors of Agile include:
- The time-boxed approach.
- Continuous improvement.
- Customer-centric approach.
- Rituals and culture.
- Results orientation.
- Iterative approach.