For a short read, it still had quite a bit of fluff.
Many of the arguments non-Sabbatarians would not find compelling since they rely on Old Testament argumentation which can be superseded.
That being said, the final chapter on the transferral of the day from the 7th from the 1st brings this up from a three star to a four star despite the fluff. Lots of rabbit trails to chase down, particularly regarding usage of the 8th day, 50 day/year, and the parallels between Sinai and Pentecost as it relates to the day of worship.
“If, even in a state of innocence, the Sabbath was a blessing to man, how much more is it necessary for him in a state of sin, degradation, and toil?”
-pg. 13