Microsoft BI benefits from the ubiquity of SQL server and the set of tools built around the database, including an ETL layer, master data management, data cleansing, report and reporting.
The reporting engine is SQL Server Reporting Services which does not have the visualization capabilities of visualization tools like Tableau or Qlik. Excel has historically been the platform visualization tool. Power BI for Office 365 has done much to improve the discovery and visualization capabilities of Excel.
Microsoft now offers Power BI cloud as the visualization platform with geospatial 3D, natural-language query generation, and self-service ETL along with charting and other data visualizations that can be uploaded and shared through the Power BI service.
The Power BI platform also provides live access to on-premises Microsoft SQL Server instances, and self-service access to third-party cloud sources including Salesforce, Marketo, Zendesk, and GitHub. Mobility is supported through a native iPad app, an iPhone app.
This new platform is viewed by Microsoft as a visualization layer sitting on top of their earlier generation of installed SQL-based technology.