I have been involved in large, midsize and small IT and software development projects in small companies and in multinational ones. In most of these projects I have used a mix of traditional and agile project management practices. The ratio really depends on the nature of the project. I find agile really useful in software development projects, especially small ones with team size up to 10 people. Above that the question how to scale agile practices up comes into play. Actually I have had hard time trying to apply traditional project management practices to software projects 'by the book'. Agile practices would be useful in other types of projects. My rule of thumb is: if the project is predictable and planable - use traditional PM approach, the more creativity, innovation and therefore uncertainty it includes - the more I would opt for agile.