How ready is Power BI for enterprise deployment?

My company currently uses a competing data visualizer for nearly all enterprise reports and dashboards.  What we've learned from the experience is that most people do not need lots of analytic capabilities and the price that comes with such power.  We've tried Power BI and from a technical perspective it would work very well as a dashboard tool for our current and future users.

We are a SQL shop and all reporting is done from AS cubes.  We do limited RS work because we prefer the flexibility and speed to market of tools like Power BI.  However, it's difficult to determine if Power BI is ready for enterprise-wide prime time.  What we need:

• We currently serve 1,200 users across many different US locations.  We have a use case for adding 500 more users who do not need deep analytic capabilities but do need the dashboard format and the ability to drill down into data.
• The data contains PHI so reporting must be able to use our Active Directory security which restrics access by role and and location.
• SQL and all reporting tools are currently on-site.  We are interested in moving some functions to Azure but aren't there yet.

Is Power BI capable of meeting our needs today?  How can I get definitive information about cost?  Thanks!