The key aspects of a comprehensive secrets manager include access controls and permissions that allow for fine-grained control over who has access to secrets, as well as versioning and rollback capabilities to prevent misconfiguration issues. A secrets manager should also provide seamless integration with existing Single Sign-on solutions, document secrets clearly, treat development environments as proper environments, offer a single unified view of application configuration, reduce friction to increase adoption, automate application reloads and redeployments, and go beyond just secret storage by addressing processes, best practices, risks, challenges, and issues related to application configuration.