While there was a lot of good information in this book, there were also a fair number of speculative statements that were presented as fact. Much of the time the author did use the Bible to interpret itself to make his point, but other times he'd say, "And this symbolizes this..." without giving any proof that anyone but him thought this. It's basically an argument based on his own authority since he doesn't tell us where he got the idea or information in these cases.
For example, the author tells us that all blood covenants follow certain steps and include certain promises (though he never tells us how he learned that this was how the patriarch era men in Canaan made blood covenants). He acknowledges that we don't see all of these steps played out in every blood covenant made in the Bible, but he dismisses that saying that the steps are implied.
Well, one thing that was supposedly always being pledged was that each party would support and protect the other (including with military aid). To quote page 28, "So symbolically I'm giving you all my strength and pledging you all my support and protection....I'm saying, "...If anybody attacks you, they are attacking me. Your battles are my battles and mine are yours....I will help defend you and protect you." The author acknowledges that Jacob and Laban made a blood covenant, yet ignores that Laban _didn't_ support Jacob in his known upcoming (potentially military) confrontation with Esau. Nor did the author qualify his statement about defending someone with "when requested."
Another "always done" step was the exchange of names. To quote page 29, "Then as we stand there with our blood intermingling, we exchange names. I take your last name as part of my name, and you take my last name as part of your name." First, they didn't have last names back then. Second, we see no evidence of this in the Bible. Yes, God changed Abram and Sarai's names, but He also changed Jacob's name (and not during a blood covenant swearing). Yes, God was called "God of Abraham," but not until his grandson, Jacob, did so and the next "God of Abraham" reference is "the God of Abraham and the God of Nahor," yet God didn't enter a blood covenant with Nahor. So God's supposed "name exchange" from "God" to "God of Abraham" doesn't appear to have been a direct result of the Abram & God blood covenant ceremony.
So, basically, there was some good, biblically grounded arguments and insights, but also a lot of unsupported speculation that I couldn't know was true or not and other statements that I outright doubted.
"Our Covenant God" by Kay Arthur also covers blood covenants and her take is more solid and supported. "Living a Life of True Worship" by Kay Arthur, Bob Vereen, & Diane Vereen does an excellent job of showing the Bible-supported symbolism of the tabernacle. Also, "The Feasts of the Lord" by Kevin Howard and Marvin Rosenthal explains the new testament fulfillment of the Passover (and other feasts of the Lord) in a more historically and biblically supported way.