I present several times per month and being very familiar with PowerPoint, I get the best of both worlds using SlideShark. It allows me to create my presentations in a medium that I am comfortable with while having the "compactability" of the iPad without losing any of my design.
The transitions are page by page so if you are looking for individual and custom transitioning, this may not be right for you. If, however, you can get by with full slide transitions, Slide Shark offers a very simple and precise conversion system to get the job done.
A great purchase for my needs!
Glenn893 about SlideShark Presentation App, v3.4.0