Oracle Reports is a reporting tool for producing pixel-perfect PDF output. It also supports other formats like HTML, RTF and XML. Oracle Reports consists of Oracle Reports Developer (a component of the Oracle Developer Suite) and Oracle Application Server Reports Services (a component of the Oracle Application Server).

Pro
With a very sophisticated format model, an experienced developer can build just about any conceivable report with pixel precision. Report triggers allow the report developer to specify PL/SQL to be executed at specific points during the execution and formatting of the report (e.g. before report, between pages). Format triggers allow the developer to specify PL/SQL to be executed before the formatting of individual items (i.e. the formatting attributes of every object can be changed dynamically).

Oracle Reports contains good wizards that allow a beginner to quickly produce fairly good-looking reports, and comes with very good documentation outlining how to produce a wide variety of reports.

The reports server contains scheduling and caching of reports, and it is possible to start reports programmatically (for example from a database trigger).

Con
Oracle Reports is a power tool with a steep learning curve. The user interface for modifying reports is not obvious and most beginners are unable to make more than trivial changes without formal training or access to an experienced Oracle Reports developer.

More Info
Refer to the Oracle Reports page on OTN for more information.