Catez Stevens has done an excellent job of outlining the basic doctrine that the Pearls teach. Although Created To Be His Help Meet isn't a book "about doctrine," their doctrine permeates the book nonetheless.

Also we must ask ourselves if we should be learning how to have a godly marriage from someone who doesn't even teach Biblical essential doctrines (vs. secondary ones such as paedobaptism vs. credobaptism, instruments in worship, etc.). If this were simply a "how-to" or self-help book, it would be different (such as Dr. Laura's The Proper Care and Feeding of Husbands). But CTBHHM is supposedly God's plan for marriage, so we must make sure that the author teaches correct essential doctrine. (Wouldn't Phil be proud? LOL!)