Another benefit of it being a web-app is how simple it is to collaborate on presentations.

Accessible online so all your work stays online (in case your computer breaks) while it has a cool and easy to use templates and designs.

Prezi helps you create presentations that tell a story. The UI lets you create a storyboard for the presentation so it's really easy to design the big picture for the presentation and then drill down to the individual "slides".

Instead of being constrained by individual slides, Prezi lets you input all the various text & media you want to cover and then organise it into a logical flow later on.

There is a fully featured web-app as well as apps for Windows, Mac & iOS (iPhone & iPad). All the files sync across the platforms platforms so you don't need to worry about managing files etc.