Like LD, I have had some students use Prezi for their presentations. Not sure if they used the online cloud version or Prezi software. (our uni classroom internet connection is spotty at best, but they were running it from their own laptops.
My impression...It's different than Powerpoint or my go-to Mac Keynote....But it made me dizzy after a minute or two of watching. I wasn't impressed. I like to know where things are going, not getting spun around with visual tricks. In MBTI parlance...I prefer linear to global learning when it comes to my presentations.
And not having used it at all, I don't know how well it can or cannot handle embedded content like videos and audio which make up a significant portion of the Keynotes I create for my lessons.