The answer to this question depends upon the type of "power relationship" it is.
Power relationships in a family are generally advantageous for everyone. Parents assert their power to ensure that their children grow up healthy and well adjusted, and those children are then equipped to do the same for their children--or serve as caretakers for their parents one day, if necessary. The disadvantages to these power relationships, as in any relationship, only come when the power is abused. That is when families deal with child abuse in its various forms or when children are forced to assume the parent role because the adult is suffering from addiction or a debilitating mental illness. This reversal of power forces children to become adults too quickly and warps their mental and emotional development.
The workplace is full of power relationships, and when people do not abuse their power, things generally work to everyone's advantage: effective output and production in a satisfactory work environment. The disadvantages are obvious: harassment, bias, discrimination, loss of job, and abuse.
These same advantages and disadvantages apply to teachers and students, pastors and parishioners, officers and recruits, among others. The potential dangers in these environments also include activities done in secret or through threats, neither of which is an acceptable use of power.