The P'Kal is pure genius. It's the best, IMHO, SD folder extant. Not only beautifully made, but designed by men who know what they're doing. The only drawback it has is blade length when dealing with heavy winter clothes.
HOWEVER, its utilitarian applications are few. Sure, you can open envelopes with it, but it's meant for stabbing and ripping the flesh of an adversary. If you can't carry a gun, or a fixed blade, for self-defense, and you're willing to study the technique associated with it, then the P'Kal may be for you.
If you need a knife to open boxes, whittle tent pegs, carve a roast, etc., the Military is more your speed.