Please update for iOS 8!
Great App, awful instructions
Once you have figured it out, it is very easy to advance or retreat the slides in a PDF file (I always convert my Powerpoints into PDF format anyway).
You set up the iPad to be the "Presenter" and the iPhone to control the presentation as it appears on the iPad. There is NO lag whatsoever between the two devices.
It also has a handy little laser pointer that you control from the iPhone.
The instructions were obviously written by someone who's native tongues is NOT English.