The Good: This is a good book to get if you don't plan on doing the footwork yourself. It is a great resource to have, even if it sparks your imagination to go further.
The Bad: This is just the Race section of the 5E PHB copy/pasted with a (much needed) line drawn down the middle. You're going to feel like you've already spent money on this section.
The Good (expanded): I like this book. 5E (and D&D in general) really needed something like this. When Tasha's said they would have something to modify your race's upbringing, THIS is what I was hoping for. I greatly dislike Tasha's idea of "just put stuff where you want it."
The Bad (expanded): I feel I paid twice as much for what I got. There really isn't a lot here and I think a reasonable person would come to the same conclusions on their own. I probably would have drawn the same line the authors did if I spent an hour looking at the Race section (maybe I would have moved strong stat bonus to Acenstry and kept the weak one with Culture). Obviously I didn't do this because I didn't feel like it.
I do like this book, but I hoped it would have been something more. This may sound like a negative review, but only because I had high hopes for this book.
Ideally, I would have preferred a "lifepath" system where your ancestry gave you some default stuff - like Elves being naturally resistant to charms - and you followed/rolled on your culture and gained skills/feats/special abilites/whatever.
If not that, then a big point buy system (stats and cultural stuff) with a "lifepath" system that gave you discounts to buy things, like spending time in the Dwarven Army let you buy Dwarven Combat Training at a discounted price while being imprisoned in a Dwarven mining camp gave you discounts to purchase Stonecunning, or something.
[3 of 5 Stars!]