I have finished around 50% of the SC course from E-GMAT and here are my views so far. As a stand alone product it is quite a good resource for the price ( especially when bundled with RC, IR, CR and grockit) however for those like me that have covered the SC guide books (
MGMAT or PS/Veritas etc) their may not be much of a stimulation as far as new material, or tactics concerned..In fact to expect such a thing will be unwise as most of the text books do a good job at teaching Grammar that the GMAT covers and so does the E-Gmat instructor... I would have liked some more GMAT like questions..Maybe give 10-15 questions per section instead of the usual 4-6 .. If you are all ready scoring around the 75th percentile, and are good in SC then the E-GMAT will not help you much. I was in that range, and most of the topics were revision for me. I started off wit the diagnostic test and scored a 86%. I decided to go ahead and continue my paid subscription for it seemed like a great revision resource, and i hated going back to the SC book that i have all ready covered 2-3 times.. Along the way, i was able to pin point areas of weaknesses in SC, which i would not have been able to do unless i took multiple CAT's.... Overall i think the SC course is great to start of with (Starting SC prep ) and not a bad revision tool for those that are scoring 70+ percent in the diagnostic and have covered prep material once..For those that do need a major push in SC i would recommend going over the basic grammar books, as it is unlikely that the
E-GMAT course will offer anything new unless you are the type of a student that responds better to a tutorial as compared to reading a text book.
Overall, my rating would be 3 on 5..I would have liked more GMAT like practice questions for the price , or at least a practice question bank. I would also recomend their test makers to lay off fromthe WSJ and Mayan civilization articles as i would love to read about topics that are a bit more diverse

(this is where the GMAT is super - at presenting topics in SC, CR and RC that are interesting to read )..