I have to totally agree with that last post!
Ive passed all 14 exams and did it thru Oxford.
I found their textbooks to be EXCELLENT, and their feedbacks just as superb!
I went thru all the books a couple of times, but when I finished the last book I had forgotten what was written in the first i read
so this is were the Feedbacks comes into play.
They refresh your memory quite effectivly.
When I did my groundschool and the following exams, several people failed MISERABLY coz they depended on feedbacks only and didnt really bother to read the books beforehand.
The Feedbacks makes you do problems in a manner you havent thought of before (espesially Navigation) that will save your day since your pressed on time, but it require that your quite familiar with the theory beforehand.