I would like to offer some candid advice/ feedback to those taking the GMAT now. I was a MGMAT student in the spring time in New York and had an excellent experience. I would, however, like to offer my feedback of MGMAT verbal strategies specifically.
Before offering this feedback, I would like to notify individuals that I used:
1) All MGMAT guides
2) Math and Verbal GMAT Review OGs as well as GMAT Review OG 11th Edition
3) Kaplan GMAT Premier Program 2009
4) Kaplan GMAT800
5) GMAT Prep online materials (from GMAC website)
6) Peterson's Master the GMAT 2009
I worked through every single problem in #1-5, and took three written exams in #6.
The "Sentence Correction" (SC) guide is extremely comprehensive, and the best amongst all SC reviews that I used. The guide covers all major topics and SC pitfalls, and provides a comprehensive list of preparatory questions. I found it useful to read this guide thoroughly, as well as to make notes and to review them regularly.
For the non- SC guides, I believe there are better ways to attack GMAT problems than those listed in these guides. Specifically, I believe that the Kaplan strategies are superior. I believe that in "Reading Comprehension" (RC) and "Critical Reasoning" (CR), too much time may be wasted by making the "headline list" and "skeletal sketch" (RC) and the "premises and conclusion" list (CR) that MGMAT suggests. I believe these are useful strategies if verbal timing is not an issue - however, in my case, I found myself running out of time on CATs when using these suggestions, and thus began consulting the Kaplan guides for more time-effective strategies.
The Kaplan guide offers methods to attack CR and RC questions that are involve paying attention to key elements in these questions, and that resulted in saved time and fewer mistakes for me. While the Kaplan CATs are very difficult, I believe that cracking these is a good indicator of success (I found the verbal section to be harder than that in the actual exam). Furthermore, GMAT800 is an excellent supplement for difficult math and verbal questions alike; it also helps to do GMAT800 questions multiple times after you've forgotten the exact answers. Furthermore, it pays to go over the correct answers to questions you got both correct AND incorrect.
I hope this is helpful.