“GPS units are like friends with personality quirks that sometimes can be hard to figure,” writes Bob Karlovits in the Pittsburgh Tribune-Review. “They know all the answers. They are insistent on telling you them. They never admit to being wrong.” Karlovits goes on to review four navigation systems based on their ability to manage the local road network. “We wanted to look at how reliable their method of navigation is in Western Pennsylvania, where rolling hills can make places virtually hidden, roads have emerged from cow paths, and sets of steps are ordained as streets.”