I lost my fabulous Suunto m-3dl compass this late summer. The great thing about it was it took very accurate readings without you having to get the thing very level. A big deal when you are in a hurry, tired, at night or anything else that competes with your concentration. I bought a cheap starter compass that in comparison just sucks. You have to be very careful not to get a false reading when its not quite level enough for the needle to swing free. It is a Silva. I am sure their better models don't share this trait.
Anyway, yes, you have to take care to keep magnetic things away form it when taking a reading and know its quirks if it is sensitive to how you hold it.
I use mine a lot to follow contour lines. Without the compass a contour line can take you right around the mountain. Without the sun or another slope to watch to maintain perspective, you can end up heading south when you started north. The compass tells you when to start to peel off the contour line to maintain direction.
Of course, at night its like a soothing, friendly voice of calm in your ear when you need to concentrait on keeping from breaking your leg climbing over the 100th blowdown, your are bone tired, and just want to be in camp already, not worry about direction. Let the compass do that.
Joshua