Although Batsford didn't design it this way, this book would make the perfect Volume Two for Soltis' Studying Chess Made Easy (see my review there). The reason I suggest this is that Soltis gives great general study tips, but the exercises are paltry by comparison. Here, Gaprindashvili does a masterful job of presenting some of the most important Master and advanced club level "turning points" in heavily diagrammed fashion. The analysis is superb, and each section gives annotated "turning points" you need to solve by theme. Like a puzzle book on steroids, these give "Priyome" type examples, some of which are the only best move, but all of which are "critical" turning points in the game. Paata states that there are only 2-3 of these in each complete game, and if you can recognize them, you can become a much better competitor very quickly. When you get to the exercises, the difficulty level goes WAY up. Unlike puzzle books, there are no "themes" and the solutions bounce across all the previous chapter topics, making you work for your pattern recognition gains in spotting those key moments. To give you an idea of the amazing balance, the book is about 250 pages, the first 100 are explanations of "critical moment" theory with 150 exercises in those chapters. The entire rest of the book -- 150 pages-- are 120 more exercises with extremely detailed explanations in the "solutions" chapter -- which is more than half the book!
Dvoretsky says that the difference between an advanced club player and a Master is the ability to manage rook endings. That may be, but to get to the advanced club player (consistently winning) stage THIS is the book you need! After that, go ahead and invest in Dvor's Dvoretsky's Endgame Manual or Tactical manual, but you'll win far more games, and require far fewer rook endings, if you seize upon the critical moves mid game. Paata divides "critical moments" into 5 categories: 1. General recognition skills 2. Struggle and capturing the initiative 3. Developing initiative (tempo) and attacking, 4. Creating counterplay, advantage and seizing the initiative and 5. Delivering the decisive blow.
Is this strategic or tactical? Both! The "critical" triage in the author's mind seems to be at the transition from opening to middle and middle to end, as most of the examples start between moves 13 and 26 in the diagrams. If you have the energy, any level of player can benefit from this book:
A. Lazy Beginner: Ok, don't worry about working that hard. Instead of trying to find the critical moment yourself, take three practice boards that don't bounce around (eg: Drueke 877.10 Magnetic Chess Set), and simply play through the examples. Both your conscious and unconscious will pick up the "gist" of how crucial turning points happen in hundreds of games.
B. Club Player: Forget, for a moment, your "favorite" secret weapon. This will take you beyond the Sicilian into the uncharted waters of many positions with no clear book play, but one common feature-- a very brief chance to maximize your minor pieces' positions at the expense of your opponent. Yes, these have "payoffs" of pins, forks and great pawn structures, but it goes beyond that, to give you a general feel for why that "hmmmm. I just think this went from equal to losing..." comes from, in specific moves.
C. Master: Think of this as a puzzle book on adrenalin. It will be great fun to see if you can spot the critical moments, and if you pick a good but incorrect line, will refine your pattern recognition greatly. This was targeted for advanced club players, but I'm at a weak Master level and got a LOT out of it.
Final advantage: A LOT of very current examples and exercises. A quick trip through the best and brightest without having to plow through the Informant, with the plus of much more detailed analysis than you'll get with Hiarcs or Fritz. For the price, a GEM.