The power of the Visual Composer, besides being a fully web-based tool, is also in integration potential. For example, with the BI Kit you can take an analytical report from SAP BW and integrate it with SAP R/3 data.
Simplicity and guidance when creating your own BI query using one of the templates, tailored for the specific business question, are other advantages that the BI Kit has to offer for business analysts.
There is a presentation that demonstrates the BI Kit capabilities: BI Kit for SAP Netweaver Visual Composer.
Additional documentation is found on the SAP Help Portal -> Documentation -> SAP Netweaver -> SAP Visual Composer
Download the SAP Netweaver Visual Composer: http://service.sap.com/patches -> Entry by application group -> SAP NW Components -> select SAP NETWEAVER -> SAP NETWEAVER 04 -> Visual Composer -> Visual Composer 6.0 -> NT/I386 -> MS SQL Server