Showing a portfolio on an iPad is great if you are doing it one-on-one, or if in a group setting, you have a connector to plug into a larger display/monitor, or use Airplay on an Apple TV enabled display.
Personally I think unless you are showing some interaction or iOS function that can only be seen on an iPad, the constant finger swiping (not to mention fingerprints) and limited viewing angle of the iPad is a distraction for your audience to absorb your information.