Fantastic
I read Boundary Stones last week just after receiving my copy. It was fantastic, and almost exactly the book I'd wished for in several discussions.
It's very difficult for some Christians to get past the idea we observe Sabbath, take the entire Scriptures seriously, and still consider ourselves followers of Jesus. I believe this book will be an excellent gift for those who don't cover their ears and start screaming "legalist!" and refuse to listen. I already have a few people in mind to give copies to.