The "Dr. Joe" books are all very readable, interesting, informative, and bring some much-needed scientific rigour to the realm of "popular science." As a chemistry professor at McGill University, one of Canada's most prestigeous schools, Schwarcz brings a couple decades worth of authority to his books. That's not to say that they are dry and simply factual - they are extremely user friendly and require no science background to understand. That is the genius of Dr. Joe's books - they are easy to read but never scientifically wrong.
This particular book contains a number of short (usually ~1 page long) questions and answers on everything from the origin of the green colour in potato chips to the use of dirt in treating tuberculosis. With 177 short essays, there is something to interest everyone. Unfortunately, they are numbered 1-177 and proceed with no other subdivisions. While this makes it easy to read in short bursts (it's ideal for city bus rides, for example), the book lacks cohesion. There are some interrelated questions that are separated in the book, when links between them would help the explanation of each observation. What he loses in coherence, however, he makes back up in variety.
In short, this is a fun book for anyone interested in how the physical world works. It also contains a number of ideas for science fair projects, for example, and so could become a valuable reference in addition to an interesting read.