This is the most compact tool Ive seen that measures both UTM and Lat/Lon coordinates. I like that all the scales are right on the edge so you can use them to mark the map. Have the people selling scales lost in the middle of a plastic sheet actually tried using them? The slope indicator is great for reality checks of planned routes.
The dual UTM scales makes dealing with UTM coordinates (my favorite system) a snap. The Lat/Lon scale gives great accuracy in a difficult-to-work-with system. I can now plot Lat/Lon coordinates faster than most people can wade through their GPS menus to change coordinate systems.
Ive tried printing various free downloads on acetate, they never last long and the scale is never quite right. The Quad Tool looks as though itll never wear out, Ill probably lose it first. It took a little while to figure out how to use the tool, but with some practice, it became second nature. The Quad Tool has become the only tool (besides a compass) I find I need to use on topo maps, both at home and in the field.