There is now a pre-built content pack that you can add to Power BI to make dashboards of your Project Online data.  Theresa Palmer of Power BI team has posted a blog on this at http://blogs.msdn.com/b/powerbi/archive/2015/11/18/explore-and-monitor-your-project-online-data-in-power-bi.aspx 

Or for an MVP take on this you can review Paul Mather’s blog post at https://pwmather.wordpress.com/2015/11/18/projectonline-powerbi-content-pack-available-bi-office365-ppm/.  Another Project MVP, Treb Gatte has also been pretty active with BI topics on his blog – http://tumbleroad.com/blog/.  I’m sure many other MVP’s either have or will be blogging this topic – so apologies if I haven’t mentioned yours.  Hopefully I’ll get time for a Fall roundup of all MVP blogs shortly (what happened to summer???)