The Power User role is specified at the user-level and applies to all jobs for the practice to which they are assigned.
The Power user has full permission at the job-level equivalent to having a job role with all rights granted (at the job level). Essentially the power user is an Administrator at the job-level.
However with the introduction of Banking Integration and new Banking actions all users including Power Users and Administrator users will need to be assigned to a role that has Banking Group actions ticked in order to be able to perform those Actions.
As such you cannot use the Power user role if you want to separate duties such as printing cheques or approving and posting batches. The Power user may also add permissions to other users.
The Power user does not have any access to the practice, static data or application settings (usually the domain of the system administrator).
The user will need to restart the application before the permissions are applied.