To give you the idea, here's an example Prezi I found on the www.prezi.com web site...
A few observations about using Prezi:
I can still work my way
When I use paper I like to jot my ideas down all over the place. In Prezi I can still do that, then I can define a 'path' around the page to turn it into a linear story... If I want to. Alternatively I can decide the sequence on the fly with my audience, depending how the session's going. So, in PowerPoint I'm forever cutting and pasting and reordering slides - then once I'm done I'm in a linear straightjacket. Prezi is much more flexible.
I can work quickly
If I want to include a Youtube video, I just can paste in the link to it and it's there in my Prezi instantly. Once I'm done I can embed a Prezi into a blog [as above] web page or Moodle page [see my rough and ready video demo of embedding Prezis into Moodle)
Provided I've got a web connection I know I can always get to my presentation. If II'm paranoid about web access, I can download it and run it offline provided I've not embedded Youtube videos into it.
There are lots more pros including: the ability to collaborate remotely with others in real time to create a prezi; using zooming to reveal hidden facts or figures; the ability to zoom out to see the whole picture so you can tell visually how much info you're dealing with.
I can't think of a downside except that if, say, the company who own Prezi.com decide to close their site, I'll lose all my Prezis. Note to self: remember to download each Prezi once it's done in case the worst should ever happen.
Lastly, a well crafted Prezi simply looks 'the business'. Here's a video explaining how you can get started with Prezi (or try http://prezi.com/learn/ for more tutorials).