Evaluation (often shortened to 'eval') shows your basic/relative evaluation. It is displayed when you use the 'score' command.
Basic evaluation reflects your statistics and skills. It does not necessarily indicate a player's power, since a high charisma or a high skill in embroidery can give the illusion that a player is more powerful.
Evaluation is not an approximation of the power of a character, only a ranking of the amount of experience they have spent. The consider command is still recommended to get a better determination of the strength of a character.