I would say GMATPILL is good for few things because it more of tips and tricks to answer the problem. But the questions with wordiness, clarity or idiom concepts then GMATPILL method fail to address and i hope even no other study material cover those things. If you are expecting solid Grammer rules then GMATPILL is not the right thing to do.
Zeke - Can you please explain what smartmundu is trying to say?
What smartmundu is trying to say is this: we explain everything in very easy-to-understand terms instead of using fancy grammatical principles and labels like "participial phrase" or "subjunctive clause" in our explanation - we believe these fancy words just further confuse the student.
Memorizing these grammar rules is not the right approach to GMAT. Instead, we teach you how to think - how to identify the important parts of the sentence and how to stay away from the FLUFF of the sentence that wastes your time. If you take a look at the many email screenshot testimonials on our homepage, many students say they still don't know what these fancy grammar terms mean - yet they were able to score 700+ or make a massive improvement to their score.
So if you are expecting to memorize grammar at the PhD level, then GMAT Pill is not for you. We specialize on quickly fixing sentences and moving on to the next one in as little time as possible. If you are a busy professional with limited time, this would be great for you. In short, we specialize on SC questions for the GMAT - not a Master's degree in English.
These skills will be with you for a lifetime in business in which recognizing sentence errors in business documents is more important than labeling them as a "superficial parallelism."
Also note that the previous post was posted a while ago. Since then, we've added many upgrades that further tackle areas like idioms that are harder to put rules on. These are the same questions that smartmandu says no other company addresses. You can see some of these idiom frameworks in Core Framework #5. We also have strong emphasis on meaning. These upgrades, as well as the Practice Pill Platform and iPad app, have been provided to existing users all free of charge.
For a sample of how we attack SC questions, take a look here: http://www.gmatpill.com/gmat-practice-t ... -questions
Note this is only one portion of the SC Pill. The frameworks and quizzes are elsewhere.