I think the reviewer was right. Slaves were treated terribly, like, well, slaves, but it was economically counterproductive to physically damage a slave and reduce their productivity. Because of the prohibition on importation, by 1860 slaves were extremely valuable in the currency of the day. Indeed, most Southerners could not afford to own a slave.
It is worthwhile to read “A Sketch of the Laws Relating to Slavery in the Several States of the United States of America”, George M. Stroud, 1827
I saw a copy of one of my ancestor’s will and he bequeathed his “negro” to someone. I found it to be quite chilling but they were considered property. Not something any of us are proud of.
It made as much sense to mistreat a slave as it would to put sand in the crankcase of your tractor...
Sure, there are always a few, but no one had TV, electricity, air conditioning, or (as a rule) running water in those days.