First, from what I've read, it seems like the most common ways folks get into a survival situation is (1) getting lost/disoriented, and (2) getting stuck unexpectedly (snowed in, darkness, fog, crash, imobilizing injury).
If someone is truely lost, it honestly seems to me that without (1) some idea where you are - which would mean you're not really lost, (2) a good map of the area and landmarks for triangulation or visual identification of your location, or (3) a GPS, the compass will, as said, only help you get more lost in a straight line.
While some folks get all nuts over the inclusion of a GPS in a kit, even the most basic GPS is sooooo much better than a compass alone at helping someone who is lost to become, well, unlost. Of course they are only useful IF the user saves a waypoint for their "home" location (whether that is a car, tent, cabin, ...).
While a map can certainly be used to help someone get "unlost", it requires a certain amount of skill and a set of identifiable landmarks.
The Garmin Geko units are amazingly small and lightweight and really quite powerful for getting "unlost".
As mentioned, if someone is truly lost, a compass, by itself, will only allow them to walk in a known direction and in a straight line - assuming the terrain allows it. Now, if you're carrying a GPS, it will tell you the bearing and the distance to "home".
With that in mind, it is critical that a compass be carried and that it can be used to follow a bearing reasonably well. Each person needs to evaluate that for themselves as some folks can do wonders with a simple button compass.
Of course I'd also recommend carrying a spare set of batteries for the GPS used.
