Prezi is now much more based on skill than chance. I’ve just started using it again, and I have to say that it is much better and easier to use than it used to be. They’ve just fixed a few of the little niggles that I had last time I was using it. Last time I gave it a go was October, last year, and it was still a bit ropey, but I think it has probably just reached the point where I would happily cut over and use it instead of keynote for many things. Keynote is still quicker, and integrates better with the desktop, but Prezi suits where I’m coming from for teaching.
The Prezi I built for a lecture on chance and skill in game design.
The other great thing is that they offer a free, educational tier in their pricing model. Though four, purely text based, prezis take up nearly 10% of by 500Mb. So if I start bunging images in (something I want to do) I wont get very far.