The new document validation feature in MongoDB Compass 1.5 allows users to easily create and modify validation rules for their collections through a graphical user interface, making it more accessible to both developers and database administrators. This feature provides significant flexibility to customize which parts of the documents are validated, including checks on attribute existence, type, format, and range. Document validation can be used to enforce constraints on specific attributes or all data in a collection, and it adds negligible overhead to the system's performance. While document validation is a powerful tool for ensuring data integrity, it should not replace application-level business logic and validation, as some checks are best made within the application's code.