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 cannot scan gc.com and pick out a few caches to go and do whilst laying in bed. I cannot use my GPSr to create a pocket query whilst sat almost anywhere, and I certainly cannot download the pocket query straight to it on the fly and have all the caches available to me immediately. I can with the phone. My GPSr can only store 500 waypoints, the phone has no limit to the amount it can store (not an easily measurable amount anyway). I can also log the caches on-line wherever I am... just a few of the good points.