When I decided to take the GMAT I was already working in an demanding internship. However I felt like I wouldn't have the energy to search for shortcuts and tricks on every topic after coming home late. I really enjoyed the ease of use of the Economist's program, that I was able to use it on the train or subway, and the personal lessons.
The best tips for me have been the ones on time management and test taking strategy, a subject which I underestimated until the very end. Gladly Isaac, whit whom I had two lessons stretched the importance enough for me to care about it. While I had some problems with applying them at first, they finally helped me to boost my test score a lot.
If you are a very organized and motivated person and have a lot of time I do believe that the GMAT is not a big problem. On the other hand, if you are working or for any reason have to take the test within the next month or two, I think that this program will take some pressure of you.
In addition, with the point increase or money-back-offer I haven't had anything to loose with this program, but my expectations have even been exceeded by far.
The only negative aspect I can think about is that you can not repeat a topic once you finished all the regarding questions.