Real GPS technology is a large number of satellites 12,500 miles in orbit sending a very weak time signal for a computer processor to calculate the holders position in space. Most users don't know or understand that the receiver is not getting blasted with 50,000 watts from their favorite rock station ten miles away, or even a cell signal two miles away. Interference from structures will stop the signal, period.
I recently purchased a Backtrack as an economical aid for deer hunting and travel cross country. At the price, Brunton and military compasses can't and won't do the same job without a geodesic map and literally days of training - training I've had repeatedly in 22 years in the US Army Reserve. Much of where I hunt has no decent map, and overhead satellite photography is remarkably low quality in these less densely populated areas. If there is any difficulty in the woods, the real issue isn't which way is north, it's the actual distance and heading from a known point.
For the price point, the Backtrack works fine. It does not have an extremely fast response time, but given reasonable patience, it will orient you to the compass and let you know what heading and distance you are from the start point. Reasonable is up to two minutes - which is all it needed the first startup. At that point I set the home icon with the extremely simple two button controls.
I tested the unit at distances of yards and miles, and found when handled properly like a compass - held parallel to the ground with no motion - it would show equal distances and complementary headings between two points. At about 700 yards it changes to tenths of a mile, and when between home and say, a parking point, you can measure the exact distance between - straight line.
When traversing rough terrain with a unscaled pictographic map, such as printed by the conservation department for most areas, it was simple to keep aware of our position on that map and get a basic idea of the scale involved. I felt more secure with the Backtrack telling me my car was 739 yards away at 356 degrees than trusting my memory of which way an old wooded ravine might go. Again, a compass would have only told me which way was north - something I checked using a Silva Ranger model I purchased while in the Infantry school. It can't tell me a distance and heading to a known point unless I literally pace it out and recognize it on an accurately scaled map.
As for literally following the arrow, even a compass won't help you make a better decision to avoid the rough patches and get on a trail heading in the general direction. The Backtrack can't do your thinking for you.
Will a GPS show you your car's location in a parking lot? Yes, and for the price, it should. But you will have to learn the menus, operation, and still set the start point where you parked it - raining or not. Just put it on the dashboard and wait. When you're done, give it a minute, hold it flat, don't wave it around, and use normal routes. Walking through walls is asking a bit much. The Backtrack will get you there - if you can remember what you drove. At that point, you might try your keyfob.