The GPS will work fine. However many of the mapping programs on the iPad (including Maps) need the internet to download the actual map. You can end up with a nice accurate dot on a blank page. Some of these apps will catch map information, so that if you look at the map of the area you are going to while you have an internet connection, you (may) still have a map when you loose the connection.
There are some apps that contain their own maps. Most cost money, but a few are free. Navfree has been recommended by several forum members.