This is really kind of a random note, but I notice there a lot of people who post from Galaxy phones on tapatalk, so I wanted to pass it along.
The phone has been notorious for having poor GPS locking. Especially in Manhattan, I find that it rarely locks into a signal, and it is a bit of an annoyance. I was reading around, and I found that literally just opening up the phone, taking out the battery and just tightening all the screws a bit might do the trick. Sure enough, this worked.
I don't exactly know why this is happening, but if you have a Galaxy S3 and have problems with the GPS, try tightening the screws just a bit.
You may now return to your regularly scheduled lunacy.