If you have never really started your own exploration into your personal spirituality then this book will give you a good start.
However, there is not much, that is really Toltec in this book. Yes, there are exercises and suggestions around awareness but that is not a uniquely Toltec trait. Yoga, Sufism, mysticism, and meditation all use awareness as an approach to inner truth.
Not Castenada, Mares, Ken Eagle Feather, nor Ruiz have really captured the full vision of a Toltec. What is promoted as a Toltec being the awakening dreamer is only part of the story. Toltec means a master craftsman or person of knowledge. However a Toltec is also someone who knows the limits to knowledge and that no system of knowledge can bring freedom in itself. Knowledge and freedom are just more concepts if all you have is a knowledge based approach to life.
A Toltec was a seer who realized that beauty, wisdom, and movement was the way to catalyze and transcend the apparent duality of the universe (and the 'self' is part of the apparent duality). Central to Toltec thoughts were also the progression of the soul (just like in Ancient Egypt). Also primary were self-sacrifice and penitence. And if any path claims to be Toltec and does not emphasize the importance of purifying the heart that system is not clearly Toltec. (If you want to go really deep and follow me in this paragraph you need to read this book Burning Water)
But still in the field of 'Toltec' don Miguel Ruiz is a safe choice. You will not have to filter out as much as with the other sources. 'The Mastery of Love' would be a better place to start with Ruiz than 'The Four Agreements' (which carries a very negative and distracting view of the world).
When I think of Toltec I think of Tula and Teotihuacan. You really need to go to these old sacred sites and tune into the vision of the people that were there. You cannot just read books and figure out what a Toltec was. It also appears that the linguistic roots of the Nahuatl language originate from Chaco Canyon. The Chaco Canyon people were part of the Anasazi, the Ancient Ones. So if you want the full Toltec vision you need to track back into the Anasazi was well. This is deep wisdom here, much deeper than you will find in any books. And no one has written a full story of the Toltec encompassing this wider perspective.
You can read my review of 'The Way of the Toltec Nagual' to get more of my insights here.
Susan Gregg's book 'The Toltec Way: A Guide to Personal Transformation' is her better attempt to convey the Toltec orientation.
'The Complete Idiot's Guide to Toltec Wisdom' by Rosenthal should be considered required reading to get a foundational level-set of Toltec views.
If after your initial intro into 'Toltec' you want some very deep insights, short of going to the Toltec sites and walking around and meditating, you can really get somewhere with 'Burning Water' by Laurette Sejourne.