Hi inca,
The book Essential Reiki by Diane Stein (which I think is the one you mentioned) really is a pretty good book. It is well-researched at least, and is good for non-Traditional students and teachers. It gets into some things that I found difficult to comprehend the first couple times through, like the Ki Exercises chapter (a mess) and the material on Reiki and Enlightenment. I ended up making study guides for use in teaching and that helped me a lot. The book is a little contradictory in spots, but overall, not a bad text. Personally, I'm not a fan of the way she seems to dis half the human species based on sex, but that's my issue! If you'd like copies of the study guides I created I'd be glad to send them. Let me know.
Be good,
Ken