Pattern recognition is a very important skill and this classic by Reinfeld drills it into your memory by testing your ability to recognize them and trains you to calculate variations. The problems range from simple mate in one all the way up to ten moves. A great feature is that with the diagrams no hints are given, only who is to play. That's good...in a real game you don't get any hints.
Reinfeld starts out with Queen sacrifices then some typical mating patterns are covered and then ends with a selection of compositions. He breaks down the problems by tactical motif, usually starting with the easiest first. This is a good way to help you learn to spot tactics by recognizing patterns.
Bruce Alberston has converted this book from descriptive notation to algebraic, but one rather strange decision by was that he did not correct Reinfeld’s analysis with the help of an engine. Naturally, some of Reinfeld’s solutions are wrong and if, for whatever reason, they were not changed, at least incorrect solutions should have been pointed out. Or, was Alberston just too lazy to check 1001 positions with a computer?!
Except for that, this is a great book that taught a generation of players about tactics and after going through the book it's almost guaranteed that you will be spotting tactics in your own games. Highly recommended.