Well Well ! Open sources are not always free and easy to extend.
Lets discuss advantage of using that:
1) Lower initial costs
2) More flexible support
3) More integration options
4) Opportunity to extend the source code with much more freedom
and the disadvantages:
1) Open source options don't have all the features found in those products, some customers may not need
2) Integration new Add-on might be difficult.
3) Common user interfaces or data access methods might not exist
Business Intelligence (BI) Open Source available in the market (Internet) by Actuate, SpagoBI, Pentaho, and Jaspersoft