You would have to be completely concealed which is one thing when hunting animals from the bushes or a blind and another thing when trying to skewer people. Outside of a very lucky shot where you sever a major artery (something no archer should ever be deliberately aiming for), a bow is only instantly fatal if you hit the heart or lung(s). Because of how people's arms and shoulders are situated, this means the person must be either facing directly toward or directly away from you. Arrows can be deflected by bone in a way that firearm ammunition typically isn't (single bevels blow through bone but hardly anyone uses those). Arrows also don't cause damage to the surrounding tissue the way firearms do. And if you hit only one lung, the person might actually survive and be ambulatory for a while. Due to how much time it takes to nock an arrow and take aim, and since firing with any semblance of accuracy while moving with a bow is incredibly difficult, the game is up as soon as someone sees you.
Bows are great for ambush hunting stupid animals without alerting everything within a half mile radius. Outside of that context, not so much.
Source: archer