I have not used it myself, but have seen presentations done with prezi and they were amazing. You can do all kinds of interesting zooming and turn-arounds. It is a great program to know if you want to have unique presentations.
I use Presi as well as PowerPoint. It really depends on what you want to do with it but there are some cool capabilities in the program. They have some good help resources to get you started too since it is a little of a learning curve from PPT.