This is the ideal introduction for someone with little to no background regarding the philosophy of science. It is probably too simple for anyone with a bachelors degree in philosophy. Ergo, if you're a science student, who hasn't taken a philosophy course, you may like this book.
The book first sets out to show what are the primary philosophical issues regarding science. For instance, what is it that connects biology, physics, and chemistry, but not biblical studies, and witch craft. Is it method? That seems dubious, since advances are often made in the biology, physics, and chemistry, through various methods. The author then focuses on the famous philosopher of science Karl Popper, and his theory of falsification. Popper thought what made a theory scientific was its ability to be falsified. We cannot falsify whether or not God exists outside space and time, therefore it isn't a scientific claim, like the boiling point of water. Of course Popper's theory has its own problems which Okasha points out.
The next chapter deals with the difference between deduction, induction, inference to the best explanation, and Hume's critique of science and induction.
The following chapter grapples with the debate between materialism, idealism, realism, and anti-realism. Realist believe that there is an independent world, that exists and behaves as science says, regardless of whether or not humans are around to perceive it. E.g., if a tree falls in the woods, and no one is around to hear it, it still makes a sound. Anti-realist believe that science is more instrumentally fruitful, but that there are large parts of the cosmos, or our perceptual tools which are incapable of getting how the universe really is.
Finally the book ends talking about particular problems in the sciences, and critiques of Scientism (the belief that science can answer and/or address all questions).