Working thru the various sections, many of the features in the new portal are still under development. And parallel the existing native SSRS portal features. But, the future looks good. The overall interface is much nicer than the old SSRS portal. We now have the ability to view reports on a unified Power BI mobile app, that supports both the Power BI reports, and SSRS reports from the new Mobile Report Publisher.
We can hope that the new SSRS will support a new report format that is compatible with Power BI. And on the Power BI Ideas site, the team has indicated that SSRS will be the on-premise Power BI server (Jan 19,2016). We know that the new SSRS 2016 reports are HTML5 compliant. As it stands now, you can 'pin' SSRS 2016 reports to your Power BI account - but that is not the same thing as having a common report server/format. (to use Power BI, you first need to configure SSRS to connect to Power BI - using the SSRS configuration tool)