I went from not having opened a GMAT book to a 760 on my first try taking the GMAT with the help of the Economist GMAT Tutor. The whole process took me two months.
I started with the trial run and took my first test and scored a 650 on my first practice test. I enjoyed the flexibility of the program, as I am a college student with a lot of time on my hands and wanted to be able to study on my own time. I studied for around 2 hours every day five days a week.
I am an Applied Math major at school so I thought I would be prepared for the quantitative section. However, on my first test, I scored very poorly. I believe that the Economist Quant prep is extremely helpful in giving you the right ways to approach problems. Certain problems that originally took me 5-7 minutes to solve, however, after using the approaches given to me by the Economist tutor, I could solve them in 1-2 minutes.
The adaptive nature of the program is extremely useful. This way certain types of problems that I just couldn't get right originally I easily mastered and problems that I knew how to solve easily originally I didn't waste time on.
I believe the verbal prep also must be among the best. I originally scored about where I thought I should on my practice test, as I do not have strong verbal and grammatical skills. The "Stop Signs" the program used were a great way to identify possible errors in sentence correction. The critical reasoning practice problems were also great and nearly identical to the real test. I believe that the reading comprehension in the GMAT tutor was slightly more difficult than the real exam but definitely helped me prepare.
I completed a little over 80% of the course and in the last two weeks started working more on the GMAT Offical problems in the app they give. I think that using the tutor to have a solid background and familiarity with the types of problems they give and then working on official problems and tests was the best approach for me.
I didn't take as much advantage of the in-app questions and tutoring sessions as I could have. However, the sessions I did have were informative and helpful. They really look at the data and your progress in order to give you helpful and critical feedback.
I scored much lower on all the practice tests I took on the Economist program than I did on the real test--my highest score was a 720. However, I believe that that has more to do with my test taking mentality rather than the difficulty of the real tests as my highest practice score on the Official program was also a 720.
Overall I would definitely recommend the Economist GMAT Tutor, especially if you want to study on your own time.