i have this book aswell. i found the fact that the solutions aren't given to be slightly frustrating though it has it's good points aswell in that the reader is forced to analyze the variations thoroughly. i am a bit sceptical as to how much the average player could achieve with just this book on their own. i think they would need a strong player or coach to go through the positions with them to make sure they have fully absorbed them. i think Ziatdinov mentions as much in the introduction. 

the theory that mastering chess requires a thorough familiarisation with certain key structures and positions has a strong empirical foundation. whether in this book Ziatdinov lists all the necessary positions needed to attain grandmaster status is highly debatable. what is for sure is that anyone who has mastered all the positions he listed would be a strong player but this takes a long time. i bought the book with good intentions but at the moment simply don't have the time to do the work required on these, so it has gone back on my bookshelf where it has been sitting for the last few months 

i would also take issue with his suggestion to memorise the full games provided. i amn't convinced that this strategy for chess improvement has as much to recommend it as understanding the positions earlier in the book has. 

for someone who has a lot of time and the motivation to study hard, as well as a coach who they can go over the exercises with then i think this book would be ideal. anyone looking for a quick fix or easy path to becoming a master, forget it cause there isn't one.