Using it right is a little bit of a skill. Too much panning and zooming can be bad, but just the right amount makes the presentation seem more fresh and alive than a ppt.
I've been using prezi for a few years now, and almost always get good audience feedback. Like any tool, you still have to know how to use it, it will not do all the work for you.
I looked at a sample Prezi, and it had way too much panning and zooming. Of course, then again, I was quickly clicking through it, whereas normally I'd imagine there'd be a couple minutes of talking and delay between each step.
