Overall Satisfaction with Microsoft BI
Microsoft BI allows us to blend the data exactly the way we want. Using the various add-ins provided (PowerPivot, PowerQuery, PowerView), we can design clean and scalable reports to take actionable decisions. Business problems addressed? Represent into a single chart 6 different data sources!
Microsoft BI stacks up against Tableau because Tableau cannot blend various data sources easily. Tableau produces nice reports with a single data source. Today, it's not what we need. We need to easily combine multiple data sources. I would recommend either Microsoft BI or Anametrix with the ODBC connector for Tableau. With the last solution, you combine the power of Tableau (nice reports) and Anametrix (all data sources living under one single roof).
Ease of use and amazing possibilities
Microsoft BI is perfect for this type of scenario (even if lots of other scenarios can be envisioned): I need the last 2 weeks of data from the data source X and the previous weeks from the data source Y. PowerQuery will allow to reach such challenges and will be updated automatically every week.