The 15FQ draws out career implications, and potential pitfalls in terms of the work environment, the job itself, and the organizational culture. It provides a good assessment about what a person is usually like and can cover additional information on things like team role, leadership and negotiating style.
The report is based on self-perception, not actual behaviour. In the discussion we gain examples to support (or challenge) the report. It focuses more on what you enjoy doing rather than what you can actually do well, hence offering the Highlands Ability Battery as an additional assessment.