Google maps finds my location fine as does the other things you mentioned. The navigation is what blows. It is not accurate enough. Some people claim it works great because they have no idea how it is supposed to work. Just like some guy on T Mobile forums swore his compass worked fine and the rest of us were idiots because all we had to do was calibrate it. He posted a video and it was working crappy just like we said.
Samsung even agrees they screwed up and that is why they are working on fixing it. The GPS does not work fine on these phones and neither does the compass.
Try driving using navigation and see how many times it screws up.