For my urban carry compass, I use a Casio Pathfinder watch. Although it is accurate to 1 degree, and compensates for magnetic deviation, I still don't trust it enough to take it into the woods. Anything with batteries is obviously a weak link. It works as good as any other compass I've used. It is affected by nearby ferrous metals, but it is not affected by itself. For my EDC, particularly in the above mentioned subway scenario, it does a wonderful job. In a real survival situation, it would be better than nothing at all, and the battery should last 18 months (according to Casio). It can be used in the dark without using a flashlight. Fallible? Yes. Better than nothing? Yes. Do I have a backup? Of course.