Im a corporate trainer and public speaker. I started with a slide projector in 1983. Been using Keynote for almost 10 years and on the iPad for 2 years. The iPad version takes a little getting used to the controls, but once you do, it is simply beautiful.
I consistently receive rave reviews on my presentations. And all this in an iPad?! Amazing!!
And yes there are presenter notes and you can add sound and video and pictures.
aldaren about Keynote, v2.5.3