Certainly the focus is on ultimate triumph and hope. Those who are to be witnesses are those who witnessed the events of Jesus' ministry, death and resurrection. The rest of us are not eye witnesses, but secondary bearers of their testimony. The key aspects of the testimony are the name and the forgiveness. The name is the person and his power.
Forgiveness is the primary benefit.
This includes forgiveness of sins. It is radically simple. The canon of scripture offers us much more than this, but this is a model which continues to speak to people. Its inspiration is in the parables, like those of the Good Samaritan and the Prodigal Son - ultimately in Jesus, himself.