Pilot here. Bought my prime to be an EFB. All the pilots I personally know that use a tablet for an EFB are apple freaks so they were my only point of reference before buying. I was told not to expect a tablet GPS to be that useful in the confines of a small aluminum cockpit. The GPS antenna really needs to be up on the dash which obviously would make the tablet a bit useless. The suggestion was to use a bluetooth GPS and set it up on the dash if I wanted georeference on the charts. However, none of these pilots bothered with that. Of course it did occur to me that these pilots were full of **** and trying to justify why they bought the cheaper ipad without 3g (and no GPS either) but I was not expecting any tablet gps to be great in the cockpit so I wasn't making my purchase decision based on that.
I'm of the mindset of not bothering with it. I have three panel mounted GPS units in the airplane. I really don't need another. It's easy enough to just swipe chart to the right location when I need the chart and I don't need to actually look at a chart very often at that.
So, I was dissapointed when I saw the the GPS in the prime is a no-go, but it wasn't a deal breaker for me. That said, I put in for that new dongle... it's free afterall, may as well give it a try.