I bought the cataga e-book about three weeks ago now and I have read it thoroughly , although it is in my interests not to get other people to buy it - I don't want more people scoring better than me!! I think the advice is very good.
Apparently they are raising their prices! I'm actually glad because even less people will buy it now and there will be less competition in the exam!
The best section in the book - I think- discusses the methods test writers use to disguise incorrect question answers. This is the sort of advice that is not common sense, the people who wrote this section have obviously been test writers themselves. They have a list of words which you should look out for which serve as red flags for answers.
The practice tests were excellent...almost identical to the official test in terms of difficulty.