Greg, I'm going to assume you're not instrument rated. EFBs are NOT for IFR navigation. They are WONDERFUL for situational awareness. Almost too good. When you're flying a DME arc, it's hard not to look where you're at in relation to the arc, especially when you have to look at the approach plate. Hold entries are another one.
Even if GPS wasn't a thing, an EFB like iFly would be unbelievably useful so you don't have to carry all the paper charts & plates & replace them every few weeks.
It's not the the CFII doesn't want me to use the tablet, in fact he agrees that it'd be stupid not to, and he uses one both to instruct and in personal flying. The issue is that DPE's will often ask that the icon be turned off to make sure you're navigating on instrument, not on the tablet, so I need to be prepared to do so. It seems like it would be an exceedingly simple feature to add, considering we already have star wars icons.