If you have used reporting services, is has been a capable, if minimalist based reporting server. And in the past, perhaps the biggest problem was the inability to support any browser other than Internet Explorer. Fortunately, the upcoming update to SSRS includes support for HTML5 - with the hope that this will support all modern browsers. And, a suggestion that mobile will be supported as part of SSRS.
For those of you who have started to use the updated Power BI tool kit (see my Power BI 2.0 First Look at Redmond Magazine), perhaps the biggest change was the focus on presentation. Looking back at all of the Microsoft BI tools, Power BI 2.0 is the first to really focus on presentation and usability. And Microsoft really got this part right. But what was not mentioned, is that Power BI already has support for its own mobile apps. Will these be one in the same as the ones for SSRS, or different? [Answer: as of December 2015, SSRS 2016 will use the new Power BI mobile apps - see Use Power BI mobile apps to view SSRS 2016 reports.
And, for all of the strategy, the one part that is really missing is the core, back-end server part that will pull it all together. We still have SSRS report formats that are different from the Power BI report formats - with no indication that the two will be merged (1). And where is Sharepoint is all this? This is a great weakness. There are indications that Power BI reports will be supported on an internal server, but that is in the future. And it may, or may not include Pyramid Analytics. (see my blog posts on Power BI). (1) - 2016 update: posting by both the Power BI team and the SSRS team have indicated that evenually, SSRS will support 'managed' Power BI Desktop reports. That is great news - but what are managed Power BI Desktop reports?
(2) - 2017 - Microsoft announces the introduction of Power BI Reporting Services. For now, you'll need some cash to get the integration of Power BI and SSRS.
Still, it is great to see that Microsoft has finally decided to get back into the Business Intelligence game, and in a big way. Now, if they will only show that they are not abandoning multi-dimensional SSAS. Tabular is nice, for some uses, but not all of them.
Power BI - a HistoryTim Rodman has a historical listing of Power BI. You can find it here:
What is Power BI? - Tim Rodman