The project manager should communicate the current status of the project, including both the exceeded benefit expectations and the action plan for completing the pending functionalities. This approach ensures transparency with stakeholders and maintains their confidence in the project's progress. It also allows stakeholders to understand the context of the achievements and the steps being taken to address any outstanding issues1234.
References: This answer aligns with best practices in stakeholder communication, which emphasize the importance of clear, honest, and comprehensive communication about project progress and challenges. The PMBOK Guide and other PMI standards advocate for regular and effective communication with stakeholders to manage their expectations and keep them informed about the project's status1234.