These are actually sometime the worst things to read if you actually want to understand stuff. The publishers of these kind of popular science books enforce the rule for authors that no equations should ever appear. If authors get really upset with that they allow printing one equation, usually, E=Mc^2. This leads even talented authors to water down everything with faulty and many time absurd metaphors. There is no real substitute to reading real physics books. On a lighter side, check this out: http://www.youtube.com/watch?v=w5VVEw4ZSRI
Well, having an intuitive understanding goes a long way too. Being able to derive formulae rather than just having them memorized is good. Of course, I don't want a book that doesn't include the formulae, but I want to know the "why" of it as well.
