I grew up watching my Russian grandmother knit everything from the top down. In fact, like many Russians, she's never even considered knitting from the bottom up. I myself have always been too scared and lazy to bother with calculations, so I followed printed patterns. I don't find grafting and weaving difficult, but at the same time I found that adding seams to babies' and kids' garments is unappealing. If yarn is bulky, and the size is small, seams become obtrusive. So, I got B. Walker's book, read it from cover to cover, and now I am knitting a skirt from it for my little daughter. The book is absolutely clear and comprehensive without being too wordy. My only "complaint" is that it has no pictures of actual garments, only diagrams. I would have loved to see some pictures of the described designs.
Beginners, take note - this book assumes that you know how to cast on, cast off, increase, decrease, etc. If still unfamiliar with basic techniques, you will need another intro book.