I started testing ReportBuilder quite a few years ago but I switched to FastReports a while ago and have been very happy with the change.
One of my requirements was that the reporting engine needed to be just one form of output (producing columnar or similar reports), but my framework needed to be able to output to this engine or an engine to produce filled in PDF forms or reports in Excel format or other kinds of digital reports. The reports have to be instances of a report superclass so that they can be combined and produced together as a package with multiple output types and destinations.
I am not an ace programmer, but I found the job could be done readily. FastReports fits into this framework and does its job superbly. I can't say enough about the power and flexibility I have found by using Delphi, Firebird and FastReports. I am just now starting to explore the possibilities of using its built in pascal scripting to integrate more completely with my main program.
I hope this is helpful.
Jack