GPS Navigation in China
Using a GPS device in China can be helpful. Personally I use Google Maps a lot while traveling around China on both my iPhone and iPad and find it to be very useful and informative.
You can set a waypoint for the location of your hotel and it makes it easy to wander around and know the direction and distance to you hotel. If you are in a taxi you can see that they are taking you in the right direction.Getting Maps in your GPS
If you have a GPS with maps of China already loading into it then you are good to go. Realize GPS units in China tend to display Chinese characters. Its useful to also have to Pinyin (roman letters) for each place. Then you can read it. The characters are handy for showing to taxi drivers.
Google Maps are useful but you have to be online to use them. If you are using a smartphone then you don't want to be paying roaming data charges to look at Google Maps. It will add up fast. If you have a smartphone or iPad you can get a local microsim card to put into your device for the time you are in China. It is inexpensive and not too difficult to do. You need to go to the phone shop with your passport and register for a card.
Note when using Google Maps to show the satellite view it is often not right, it does not match with the map view. This is a government mandate.