holding it by hand??
I mean even if it's not quite as fast on the draw updating my progress as driving, it would still be better than stark raving terror I have now!
Sure! Nothing stops a GPS from working just because it's not attached to this boxy thing with at least three wheels. So let's show you the use case first and then answer your second question ...
Use case 1:
I'm finally releasing my ye-olde-towne-with-four-roads roots and getting out to explore NYC. Problem is, it's a set of area 1000 times bigger than I am used to. But I could still manage it in places like downtown-ish Manhattan as long as it stays on the grid, or my section of Jackson Heights in Queens.
But let's use an easy case... behind the hospital is a grid ... canted forty five degrees!
So let's say after whatever you were doing there, you go get a pizza, then you make a few more turns to look at a cool shop, then you stop at a Duane Reade pharmacy to get some stuff, ... and then you discover that you have no idea where you are. Because besides forgetting what roads you took, if you try to "fake it by heading directly home" ... you're totally wrong because your guess of where home is, is wrecked by that 45 degree cant.
And then in places like the Village with its five way intersections none of which is a 90 degree angle, ... well, pretty soon that becomes nowhere land!
So you just punch up the GPS, and it WILL figure out where you are. Then you punch in home, and it WILL find a route. So your first move is guaranteed to be right direction home.
Use case 2:
So there you go, let's say you are headed home, and (making this up) you successfully turn on to O'Malley street. Which is five hundred feet long. And you're facing a V-Neck intersection of Cody Street and Mouser Way. At walking speed the GPS might not be fast/accurate enough to tell you which to take. So you just randomly pick Mouser Way. At some point it WILL finally notice you're actually on the wrong road. But then it *recalculates* and tells you the new correct direction from there is Obscure Drive. So you take that. And then I don't even need it all the way home. I just need to get to the midtown manhattan grid and grab the train I know. So yeah, you burned a few minutes with a detour, but it WILL get you home.