Poker books are perhaps best judged by characterizing the author; given this, reading Jeff Rubens' "Win at Poker" is like listening to your grandpa sermonize on his card strategy, which in this case is conservative and numbers-oriented.
Be forewarned--`Win' was written in 1968, and the game has changed since then. There is no mention of Texas Hold `em or Omaha, and "stud" poker mostly means 5-card, which is virtually extinct. Not to say that the book isn't generally correct or effective (I have caught a couple of questionable calculations that don't give further explanation), only that it isn't very stimulating, and the sample deals and quizzes aren't easy on the eyes.
`Win' is good for the amateur player who already has style and intuition, but needs to learn a bit about probability. The book's strength is its coverage of pot odds and betting odds (calculating risk vs. possibility of reward), and its treatment of positional mechanics, or what you'd better have in relation to where you're sitting.
I'd like to give "Win at Poker" more, but the fact that it's dry and dated devalues it from a `must-read' to a `might-read.'