The first book, "Small Spaces Huge Yields" is short, and seems fully contained and updated within "Marijuana Cultivation Reconsidered." I'm happy to have bought them both, the guy seems to be really thoughtful, and profits from his books are dedicated to ending prohibition. His claims about his local tap-water quality makes me think he might live in Fort Collins. Everyone I've met from that town is chill as fuck.
I've read 85% of the book now, it isn't long. If you are interested in the botany aspect, Section 1 will refresh your understanding of taxonomy, plant anatomy and physiology, photosynthesis, and nutrition. Section 2 is the practical guide to growing good weed. I'm skeptical of the usefulness of "duoponics," that's the part of the book I skipped, but I intend to read it in detail today. I'm surprised he doesn't seem to give much mention of passive DTW coco or similar methods. He does own a soil company, so maybe I shouldn't be. Section 3 is back to the science, with a discussion of basic genetic inheritance, a beginner's guide to selective breeding, some fascinating stuff about soil chemistry and compost teas, a delightfully nerdy discussion on how to measure light properly (my favorite part aside from the plant biology section) and some other bits and bobs about nutrition and cloning. There's a lot of great references listed throughout, and it is a thoroughly researched piece of work. I can't say I learned an amazing amount from it, but the stuff I did learn was pretty darn cool. Well worth the $10 for an electronic copy. I would happily own a dead-tree version of it.