Tableau is without doubt, in my opinion, the leading BI software. It's taken a lot of hacking to get Tableau Mapping up to the point where I can safely say we now have BI + GIS (viewing) capabilities +Location analytic capabilities.
But: ESRI is catching up with its BI and dashboarding/reporting capabilities, having been the "Tableau" of the GIS market for decades and is now enabling/ramping up their BI capabilities with partners such as IBI, SAS, IBM and SAP.
Don't get me wrong, I love open source software like Geoserver & QGIS, but at the Enterprise level (and for legacy reasons) ESRI makes a lot of sense. I still believe big enterprise/government just want to connect their geodatabases and blend with their data - and Tableau should be in prime position to do both.
The future sure is exciting for BI+GIS+Location Analytics regardless of what happens though.