Maxwell,
Here is my synopsis of the BGS QB from my time with them. This may well vary depending on when an exam was taken. This is my utterly subjective view of how relevant the feedback was to the exams I sat. When I say relevant, I mean that I directly recognise the question or I thought I knew how to answer purely from feedback (warning...very subjective!!):
Air Law: 70%
A/C Gen: 70%
Met: 60% (just plain tough)
Gen Nav: 40% (lots of CRP and calcs so unlikely to get the same questions)
Rad Nav: 90%
Instruments: 70%
Human Factors: 70%
Principles of Flight: 50% (weasle wording!)
Performance: 50% (as above)
Comms (VFR & IFR): 90%
Mass & Balance: 80%
Ops Procs: 70%
Flight Planning: 40% (good FB, but lots of chart work).