SpagoBI bills itself as the only truly and total open source BI platform available. Some may argue with that, considering Jaspersoft and other vendors. With its SpagoWorld support network it certainly has an interesting line of offerings.
It has morphed into a large line of BI components, including reporting, OLAP, query and analysis, geospatial analysis, dashboards, and ETL. In recent years, its expanded into mobile and cloud BI, but those technologies seem to be a little more lacking than most of the bigger vendors. There is no freely available iPad application, for example. They do have partnerships with several other opensource companies, and offer a unique open source BI appliance using MySQL, InGres and other free database setups. This integrated appliance can take some of the implementation issues out as they are completely pre-configured.
The customer set seems to be more European based and is especially heavy in Italian companies, which is not surprising considering its Italian origins. Several large customers there have implemented it as one of their business intelligence tools, including Fiat and the Italian Ministry of Health. Accor Group, a rather large hotel change, also uses it. In the U.S. the biggest named user seems to be GameBay, a larger Bay Area game developer. They seem to do better with healthcare and government clients overall though, and even have some industry application created for these specific industries.
One interesting architecture note is that it supports the use of the Mondrian OLAP server as well, so it allows some modularity between components. Another somewhat innovative piece is the addition of the behavioural model. This is a kind of hybrid security/object management piece that controls access for users to specific data and modules within the application. Its meant to control data visibility and be a kind of metadata management, both of which can be overlooked components to a BI implementation.