Ad hoc reporting greatly reduces the need of developing/customizing Jaspersoft Studio-based reports
Jaspersoft uses certain open source libraries that might have known vulnerabilities. Though it might not be a real threat in Jasper's use cases, it could still raise concern from companies that have a strict security policy.
Very important to us since we need to support a wide range of customers with different preferences of datasources and deployment types. Supporting more datasources also means it can pull data directly from the sources and hence less need to copy/migrate data.
I believe mutli-tenancy provides the additional layer of security and best fit for supporting multiple organizations with different admin and themes and would definitely be an important feature for bigger companies. We have yet to explore this but are planning to.
It's been a long time since we have been using Jasper, so I can't really remember the details, but mainly it was about comparing how easy it was to integrate with our Java-based product, reporting capability, and datasources/platform supported.