I am going to be controversial and say yes. But only because it is more a yes than a no.
I am not using an iAnything, I am using android. I do not use a Geocaching app by Groundspeak, I use non-official ones. The battery life is good. The accuracy is on par with my GPSr. The only time my GPSr comes out of my backpack now is when setting a cache to double check the coordinates, it has agreed with the phone each time so far. And I always carry the GPSr so that I have it available to include it in a photo for other location based games.
The only negatives I see at the moment is fragility and water tightness, but it feels much more rugged sat in the flip-open padded case.
Until I gave the phone a good try I was not convinced. Everywhere was telling me that a dedicated GPSr was the equipment to have. But my GPSr But my GPSr cannot scan gc.com and pick out a few caches to go and do whilst laying in bed
You go caching in your bed. Impressive