I think is a great book in terms of giving you the fundamentals to "refresh" what you have forgotten back in high school.
However, the end of chapter questions do require you to go beyond what was covered in the chapter... that is, you won't be able to attend 100% accuracy by just simply reading the chapters.

I do not use MGMAT quant material, so I do not know the comparison. However, I do think Jeff's book is reasonably priced for the stuff you get.

HTH

In addition, Sackmann responds to his emails within 24 hours. In all his questions, 1000+ I caught two errors. I told him about it and he responded within 24 hours and corrected it. On a few occasions, he took the time to explain a few answers when his were not clear.

At least when starting out, I did not like Sackmann's Total GMAT Math and promptly switched to the Manhattan Series - the best math guides available, in my opinion. As one previous poster suggested, he simply doesn't discuss the topics thoroughly enough to fully absorb the material. The questions in the book are good, though.

However, Sackmann's math sets are, without question, amazing. I purchased and studied all of them. It was the single best investment I made for my GMAT preparation.
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So between the MGMAT guides, Sackman and the OG, aiming for a 48-50 on the Quant would be a good shot if you put in the right amount of work? (I'm fairly good at Math since I am an engineer, I just need to master GMAT Math)

I scored an 18 quant on my first practice test. After reading MGMAT and practicing with Jeff Sackmann's math sets and GMATClub Tests, I made it to 48 on the real thing. I also used the OG books.

The fundamental sets are fairly simple, but it's good to do those and read his explanations, which are fantastic. Trust me, reading 1,800 math explanations helps to improve your understanding. GMATClub tests are very difficult and should be saved for last, but these will ensure a strong performance on the quant section. These are the two best sources for math questions.

I didn't like the math exercises in the MGMAT guides. I would actually skip them. Read the chapters and use Sackmann's questions instead.
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If you already have the MGMAT guides, then skip Total GMAT Math. In my opinion, Manhattan offers the best coverage of math concepts tested on the GMAT. But Sackmann's math sets are an excellent investment. GMATClub tests are free once you: (1) post 200 times, and (2) have been a member for three full months. You can also buy them.

My case is a little extreme, though. I practiced with thousands of questions, but I needed to do that in order to score well.
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this thread really helped..thanks to everyone..got a clear idea about Jeff Sackmann's math sets ..

I advocate the following formula for GMAT quant success: GMATClub tests (do them twice under timed conditions) + Total GMAT math to build concepts foundation. Jeff - the author - explains very practically how to attach each type of problem. In comparison with MGMAT, his explanations are more concise and up to the point: for example, Venn's diagrams and probabilities are much easier to grasp than in MGMAT books.

I took a GMATPrep exam and got Q47... What should I use to get to the next level ie 50....

GMATClub Tests or Jeff Sackmanns Total GMAT or Jeff's Challenge Sets or a combination of two...

Well I believe MGMAT guides are sufficient and there is plenty of knowledge available on GMAT club that you can utilise if you have the time.