We used the Shaka guide and thought it was interesting but a bit annoying, the tone is a bit too kid-friendly if that makes any sense. App also caused my Pixel 4 phone to overheat and I ran out of battery at some point despite my phone being charged by the car, ending up finding a way to blast the AC on my phone to help it. Wasn't expensive though so was still decent value for the money, we did pretty much all the Maui tours (minus some glitches and problems that prevented us from listening to some of them).

I have no idea if Gypsy is better.