Lightning Data Service allows developers to build custom components that can access and manipulate standard and custom object data without writing any Apex code. It provides a standard controller that handles data retrieval, caching, offline access, and notifications of record changes for custom components. Developers simply add the <force:recordData> component to their custom components to access and display record data. Current limitations include lack of support for some standard objects and formatted field values. The roadmap includes general availability in Winter '18 along with additional features like bulk data support and server-side triggers.