I use it on my phone. I also have a Garmin Montana with an OnX chip. I use the phone the most because I already have it with me but for detailed mapping, I find the Garmin to be considerably more accurate. I've used it a little for geocaching and it's accurate within 3'. My $200 Motorola phone isn't nearly that accurate, maybe 10' or more, and occasionally it's 10 yards off. Hopefully your $1000 Iphone will be better.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.