I will say she emphasized that everyone should try to look tall, encouraging high heels for short women, which I can't say I necessarily agree with. I think high heels on a daily basis is terrible for your body. See these articles for more on that: What health dangers lurk in your closet and High Heels: Worth the Health Risk?
Otherwise, I enjoyed her advice and took the opportunity to re-evaluate my closet. A lot of the advice you have probably heard before, but it is a pretty new book, so unlike some fashion books it is not yet outdated in its advice.
I'd say this is a good read for you if you are stuck in a rut and need to re-evaluate your closet to meet a certain goal, such as feeling confident in your clothes, having your clothes match your job or just to make sure you have all the necessities in your closet.