...What old_goat2 said...
My phone will function as a GPS anywhere a Garmin will, period.
If you don't know that then you are not reading the previous posts and don't know how to operate the app on your phone. It's worth getting to know the app, otherwise you're wasting your money.
Plus, I can literally be in the field, take a picture of a something, (a landmark, a kill, anything) and then drop a pin on my GAIA app, then upload the photo to the way point I just created... all on one device and in about a minute or less. For me it's the multi functionality of my phone and the user friendly interface of the GAIA app that makes a difference. My phone is smaller and more packable than almost all GPS units out there and does so much more!