Here's an article that I saw that points out some flaws I would consider actual flaws as well as one that none of us has thought of so far: how the heck do you give directions - especially computer generated directions - in places with no street signs? Many of my routes would have directions like, turn right just past the abandoned couch, turn left at the wino or in one place - litterally - take the path with the least wear - not one of the well worn ones and not the medium one but the one that's barely detectable; the one you can only find if you know it's there!

http://www.pcmag.com/article2/0,2817,2361186,00.asp