<p>My company is heavily invested in the MS BI Stack (SQL Server Reporting Services, -Analysis Services and -Integration Services), but I want to have a look at what the seemingly most talked about open-source alternative Pentaho is like.</p>

<p>I've installed a version, and I got it up and running quite painlessly. So that's good. But I haven't really the time to start using it for actual work to get a thorough understanding of the package.</p>

<p>Have any of you got any insights into what are the pros and cons of Pentaho vs MS BI, or any links to such comparisons?</p>

<p>Much appreciated!</p>

I can't offer any input on the MS BI Stack but at the most recent
Barcamp Orlando
, the folks from Pentaho were there and spoke about their products and it was an extremely impressive demo.
The fact that it's an Open Source project that you can extend yourself as well as a paid package for really good service leaves you with a lot of options.  They demonstrated some paid work they did for a client and they definitely wow'd the crowd.
I also had a chance to chat a little bit with a developer working on the data warehousing side of things for Pentaho and he was extremely sharp and was very open to suggestions and had no problems answering any questions.
So as far as a company goes, Pentaho really impressed me with both their work and how friendly and approachable all of their developers were.