The challange with using Google Maps with gps and no wifi is you MUST cache the areas you'll be in ahead of time. Plus, these are bit mapped images and can take a lot of space, especially if you want various zoom levels. The vector maps with Osmand can be preloaded for any area of the world, and once loaded can be zoomed in and out to a high degree. For example, recently had street maps with me for a recent visit to Tonga and Fiji just by loading the Oceania region of the world.