Best price-performance gmat course

I’ve been using the e-GMAT course for only 1.5 month, and my score has improved from 570 (Q42, V27) to 670(Q48 - V34). I’m really impressed. Thank you e-GMAT !.

e-GMAT gives a crystal-clear explanation of how to gain a higher score. The best part of e-gmat is I can learn and practice each Verbal topic (Modifiers, Parallelism, etc) separately. Features such as score data analysis also help me understand my weaknesses. Therefore, I can effectively allocate my time to improve on weak areas.
In the future, I hope they provide courses on Android platform too.

Previously I subscribed to the Economist GMAT Prep, but I couldn’t get score higher than 600. The explanation is not deep enough, the practice test is too easy and the price is expensive too!