I suppose this is more my issue than the book's, but somehow this book managed to make all of these different types of marriages sound absolutely dreadful. The idea of deciding for oneself(ves) what marriage should mean is obviously great, and my favorite parts of this book were consequently the first and last chapters, which discussed very eloquently the idea of redefining marriage and acknowledging that many of our traditional ways of thinking about it just aren't working.
But the marital models themselves just sound awful and awkward, and the chapter on open marriages doesn't seem to include any perspectives from actual polyamorous couples, just the typical "we were bored/unhappy so we decided to sleep around on the side and then realized how In Love We Really Were and became monogamous again." Like, k. There was also a mention of a "six month open, six month monogamous marriage," which almost made me throw the book across the damn lawn. I wish books/chapters on nonmonogamy would at least mention the fact that rules and hierarchies are NOT a must, and I wish they would caution optimistic and naive new nonmonog couples that *you cannot control your feelings using rules*. Behavior, maybe. MAYBE. But you can't just make a RULE about not having certain feelings. Feelings are going to happen.
Also, I'm sorry, but why the fuck are covenant marriages in this book. The subtitle is "Reshaping marriage for skeptics, realists, and rebels," and I'm pretty sure none of those three categories of people would enter into a legal agreement that literally restricts their freedom to get away from an abusive spouse. (Covenant marriages allow divorce in a few special cases, but you have to prove it and emotional and financial abuse don't count, only physical and sexual abuse.) Seriously, Google that shit if you want to be horrified. It belongs in a 17th century legal manual, not in a 21st century book on practical and nontraditional marital arrangements.
I do credit these authors for actually including same-sex couples in their interviews and discussions, which few authors do when discussing relationships (especially marriage). I also think it's pretty great that they make sure to discuss the potential downsides of all of these arrangements, except for the poly stuff I mentioned above.
I suppose that if romance isn't really a consideration for you when it comes to marriage, this book presents some great alternatives. I don't care much about marriage in any sense--to me it would just be a way to celebrate a meaningful relationship with our friends and family as well as get some sweet tax benefits--but nothing in this book really appealed to me, even as a poly person who will have an open marriage if I do get married. It's really just a bunch of different ways to write a legal contract.