What do you guys look for before deciding to buy a textbook? Assume that you don't have any recommendations for texts, or that you have recommendations for 2 or more but can afford time and money enough to buy and read thoroughly only 1 of them. Then what do you consider most important before deciding to buy a text? I'm talking about physics, maths and engineering textbooks I assume the following factors are important: 1. Practice excercises, problems with accompanying solutions at the back. 2. Favourability of reviews on Amazon.com (yeah I know this one is pretty subjective, but if a number of reviews on Amazon tell you that quite a number of numerical solutions to the problems of a textbook are erroneous, would you still buy the book?) 3. Cost and pricing of book. 4. Whether or not it's the recommended text for the class you're taking? What else should I consider?