First off, I will say that if you are planning to use just these books as your source for studying for the MCAT, I highly advise against it. That being said, these books are an extremely valuable resource for content review. They are comprehensive, but not so much that you could pick up these books and become a content expert. They are supplemental to the courses you should have been taking in college. The books do a very nice job of condensing the material and organizing it in a way that makes sense. What's great too is that they align them with the content that AAMC indicates will be tested.
Organic Chemistry - A nice overview of the functional groups and general structure of molecules. A decent representation of reactions and how to think about what to look for when analyzing an organic reaction. They don't teach you the very basics, but do refresh nicely on what you should already know. There's a level of knowledge you should probably have before you read it.
General Chemistry - Very comprehensive and a sound overview of what's going to be tested. There's a lot here, maybe too much. This is my strongest subject so I didn't spend much time with it. If it were my weakest, I probably would have found this book confusing.
Physics - Probably way too in depth for what's actually tested. They give you a lot of equations that you think you should memorize, but you probably don't need to for half of them. Only the basic ones are needed. The complicated ones are going to be given within the test itself. It's more important to understand the relationship of the variables, not the equations themselves (i.e., increasing X makes Y go down, rather than memorizing Z=X*Y).
Biology - By far the best book in the set. It's a no-frills run down of everything you need to know. Memorize the entire book. I really liked the endocrine system review. It doesn't do too great of a job of helping you think like a biologist would, in the sense that you need to imagine how an experiment would be carried out in real life. Biology on the MCAT is about interpreting data from an experiment of something you've never heard of before. There aren't enough charts and graphs in the book. The biology passages on the MCAT are full of graph interpretation. The graphs are actually much harder to read that you think they are. These books don't do much prep for that.
Biochemistry - Excellently written and breaks down every biochemical process into simple and easy to understand examples and exposés. I really enjoyed reading these. Memorize everything about every single amino acid.
Sociological Sciences - This book is okay. It seems to be a little more in depth that's necessary. There's too much background information but I though it was interesting. Extraneous but interesting.
CARS - Don't use this book. It's essentially a waste of time. The best thing to do with this book is just jump straight to the practice passages and do them. There are much better resources elsewhere (more on that).
Quick Sheets - Read them constantly, over and over again, throughout your entire study. Memorize every detail. Be able to recite them in your sleep (seriously).
The "Real World" asides are pretty cool and interesting. The "Bridge" asides are great to help you jump back to another book and read that section so you can tie them together. Remember, science isn't actually divided into artificial discrete subjects - Everything is inherently related. "Key Concept" asides are where you should place your sticky notes. The questions at the end of the sections are good, but they are really just concept checks. They won't help you much with Test Day. The online part of the package is pretty good but not really. The most useful are the three practice tests. They should be taken in all one sitting. They should be used mainly for timing and to build concentration stamina. The scores they give you probably aren't going to be realistic to how you'd actually score.
Throughout every single book except CARS, I wrote in every margin and basically put the concept into my own words. I wrote out diagrams linking ideas together. I highlighted what was important. And I put sticky notes in places I needed to make sure I knew cold. I was able to go back quickly through the books over and over again, reading mainly just my own notes. It made reviewing way easier since I was reading what I wrote, not just re-reading the stuff someone else did.
If you are aiming to score in the top 10% of test takers you NEED TO LEARN EVERYTHING IN THESE BOOKS. The MCAT is merciless - It will test you on the stuff that everyone should know, and then it will throw in the 10% of questions that basically no one knows. This is where you earn the points that set you ahead of everyone else. The answers to those handful of questions on the test are buried in these books.
Resources that should and must be used outside of these books are AAMC's materials available through their website, Khan Academy, and probably one other of your choice (Princeton Review, UWorld, etc.). I would recommend checking out Reddit for more Test Day strategy as well. Also, DO EVERY PRACTICE TEST!
The best way by far to succeed on the test is to do PRACTICE PASSAGES. You basically just have to sit there and learn how to read efficiently and know what is being asked. You need to learn your timing and develop an internal sense of how well you're doing in the moment. You need to develop stamina. How well can you sit and read for 7.5 hours? Just like anything else, you can only do it all with practice - Practice exactly how the test will be administered.
This test is not for the faint of heart. If you're going to take it, you need to commit to throwing the kitchen sink at it. These books are just one tool out of many for doing so.
Good luck!