I used this Complete Guide some time ago as well, and spent around 2-3 months on it. I found it quite detailed and comprehensive. The content was close to the real test that you may face as well. The strong point of this material is the Reading passages, and the Writing section. They were provided with guidelines and you can refer for your performance. I found it a material which is worthwhile, and I recommend you to refer to it in order to improve your proficiency and confidence.
An amazing book contains the whole tricks for all section Reading , Listening , Structure , many exrcises that support each lesson , many mini tests , 3 practice test ... I could advise every one who wants either to succed in the TOEFL PPT or to build up his grammer in English