Rating - 3: worth reading once (borrow it from a library)
I love Raymond Smullyan. This is not his best book, but there is fun to be had.
Just what it says on the cover: 225 puzzles. Each chapter takes a different bit of logic and creates puzzles that are variations. The earlier sections are more "grab bag," while they become more tightly grouped by the end.
Because of that, sections will have more or less appeal to you. Some parts of the book you will consider re-reading, because you liked those ones. Other chapters you might have considered completely not worth it. I will average those 2.5 and 3.5 bits into a rating of 3.
Mr. Smullyan is most famous for puzzles on the island of knights and knaves, where knights always speak truth and knaves always lie. We have many variations on those. He is also known for meta-puzzles, usually of the following structure: bits of information A, B, and C, then someone is asked a question; you are not given the answer to the question, but you are told that you can solve the puzzle just knowing that he did answer, which lets you figure out his answer. For it to be a perfect Smullyan puzzle, it should be a meta-puzzle where you can solve the puzzle itself but not figure out what that missing bit of information was.
Or, as Melvin Fitting famous put it, "I now introduce Professor Smullyan, who will prove to you that either he doesn't exist or you don't exist, but you won't know which."
Some of the puzzles are trivial but tedious. That is, if you know how to solve them, you will not gain much by going through the motions. Several of the puzzles are just complex algebra story problems; if you are good at algebra, this is obvious, and you move on; if not, you probably do not want to do solve them, but you are exactly the sort of person who could use that mental exercise.
You may find it easier once you recognize the theme in each section. Once a type of puzzle is introduced, the following puzzles will be variations on it. If you understood the first one (even if you did not solve it but read the explanation), you should be able to answer most of the rest. Of course, sometimes they can get rather tricky.
That exhausts what I an coherently say about a book of puzzles. They build on each other, but not the way that a story does. If you like logic puzzles, here you go. If not, maybe you should try some anyway, because you might like them once you develop better logic skills. Being able to reason properly is a good thing.