Gps ???????????

Ok I have a Lowrance 135X and of course it doesn't have GPS in it. I have been drooling over the HB side img and Lowrance LSS and downscan for over a year now. But just can't justify the cost right now. I don't want to buy a finder with just GPS capabilites and then in a another year or so be ready to get another one with the side scan.
Now to my real question. Has anyone used the new phones for GPS? I was playing around with mine and it works pretty good. Actually real good. It was faster and more accurate then my Magellan Sport Trac Pro is / was. There are plenty of applications either free or at very little cost to use. I was using a free one and marked several of my mushroom spots with it yesterday and then went right back to them as a test. It seemed to put me within about 10-12 feet. I don't know what the refresh rate is but I can set it to place track marks at less than 1 sec intervals. When walking slowing thru the woods it never once left me a donut, or anthing else to eat (sorry couldn't resist). I can place waypoints, make routes, and most everything my hand held Magellan done but with a much bigger screen. It does suck battery life quickly when using it as a gps but in the boat wouldn't be an issue as I can plug it into the charger. I was just curious if anyone else has used their phone for this.
PS: if anyone has one of them old HB side imagining finders their sick of I would be willing to help you properly dispose of it.
Everyone have a good day!!