A Data Model is a new approach for integrating data from multiple tables, effectively building a relational data source inside the Excel workbook. Within Excel, Data Models are used transparently, providing data used in PivotTables, PivotCharts, and Power View reports. You can view, manage, and extend the model using the Microsoft Office PowerPivot for Excel 2013 add-in.
So yes, this basically means better integration of the current PowerPivot technology stack into Excel. The fundamental change, I believe, from an end-user’s standpoint is that it will be installed as a core functionality of Excel 2013 – without requiring the download of an add-in. Of course, this will enable the sophisticated analysis that you should expect of the xVelocity In-Memory Analytics Engine and the DAX language. But another benefit will be to allow many more users to leverage the power of Excel’s cube functions (it so happens that PowerPivotPro has another great article on that particular topic). xVelocity, together with cube functions and the slicers that appeared in Excel 2010 completely change the face of spreadsheet report design and ad-hoc analysis.