Every time I have picked up a W.W. Sawyer book, I have not been disappointed. I mostly regret not having read his books earlier (I started with the last book he wrote, on Functional Analysis in graduate school). Sawyer has a particular mathematical writing style that I find fresh, insightful, and understandable. He uses humor, lots of analogies and pictures, and well-motivated examples to get you to learn a concept. This book is no different, and I plan on going through the rest of the catalog of books written by Sawyer.
This book covers a variety of mathematical topics, from groups to projective geometry, to determinants, and to matrices. You won't be an expert, but you'll have a flavor of what's going on. Sawyer wrote it for people thinking about getting deeper into math, and I think it would work wonderfully there (though I'd like such people to read it and give me feedback), but I have a ton of mathematical experience, and the book shines for me as well. It explains connections between various branches of math, and helps you take a new look at old subjects and just reminds me of the "beauty" (or whatever you want to call it) of math, and learning a math truth for yourself. I particularly enjoyed that Sawyer doesn't dumb anything down. He even talks about the hypergeometric functions (I have an interest in them, since they are basically every function you ever work with in physics) and he explains them without overly complicating things.
There are just a lot of great insights, humorous statements, and wonderful analogies throughout. I am so sad that Sawyer didn't write even more.