This book was really timely for me, as, against my better judgment, I was getting a bit frustrated with my progress. Good to know there's hard scientific evidence that progress in meditation roughly follows a dose-response curve (i.e. the more you do it, the better you get). It was instructive to know that different types of meditation have different benefits (and effects on the brain) and reassuring to learn that altered traits take a long time to set in, but they DO set in-it just takes time. Finally, it was simply inspiring to read about the neurophysiology of the "Olympic-level" meditators (Tibetan yogis) who have put in, on average, 27,000 hours of practice, the longest being 62,000 hours (that's 12 hours a day of practice for about 15 years!). Also informative was how Davidson and Goleman divided the expertise of the meditators according to 3 dose-response levels: beginner (up to 1,000h), long-term (between 1,000 and 10,000 hours), and world-class (12,000-62,000h). So my measly 900-1,000 hours of practice puts me on the cusp of the intermediate level, and because some books on meditation (like The Mind Illuminated, sometimes make it seem like a quicker journey than it really is, it was good to know I still have a LONG, LONG way to go (roughly 7-9 more years at the rate I'm practicing to get to the next level). Also good to know was the importance of retreats (the number of which correlated with certain altered traits, like slower breathing and reactivity to stress due to the increase in the prefrontal-amygdala connection).
All in all, good book at the right time.