I have mixed feelings about this book. It's how I learned electronics, so I can't knock it too much. However, sometimes the explanations, which tend to be intuitive rather than logical, can be quite hard to follow for someone who is more methodically-minded. So, for the nitty-gritty analog stuff in the bipolar transistor chapter of AoE, I much prefer "Design of Analog Integrated Circuits" by Gray and Meyer. It works for discrete circuits, too, even though integrated is in the name.