Presentation Structure, by Sean MacEntee: Retrieved from http://www.flickr.com/photos/smemon/5696337148/ and used according to a Creative Commons Attribution License
In addition Prezi is less linear than is PowerPoint. You can link to earlier slides in Powerpoint, but with Prezi you have greater control over the entire path.
I have nothing against PowerPoint. Used well it can be an effective tool. It works well for sequential storyboarding or outlining. Conversely Prezi may not suit every situation.
In short we want to explore different presentation options. Then we can choose the right one for our particular purpose. Harris (2011) highlights educational uses of different presentation tools, including Prezi.
Harris, D. (2011). Presentation software: Pedagogical constraints and potentials. Journal Of Hospitality, Leisure, Sports & Tourism Education, 10(1), 72-84. doi:10.3794/johlste.101.339