Generally, the Gor books are read not for the high-quality fiction (it's not), but rather as thought-experiments, that is, for the ideas, implications, and resonance with what we know and experience in our world and society. Broadly, that thesis is that our society is flawed, that those flaws come from our estrangement with the natural world and our own natures, both as individuals and as societies, and that a closer and more honest connection to that natural core would be more conducive to growing and strengthening both individuals and societies, to our better individual and collective happiness.
That the focus people often bring is the master/slave element, a subset of the Gorean philosophy presented, is not the fault of the author. Anyone reading for wank fodder will be sorely disappointed.
That said, Norman, an academic but a novice fiction writer when he set out, eschewed an editor -- which would have served many of the books well.
Within the dozens of books, quality varies. And there are subsets within--the Jason trilogy, for example, and the Blood Brothers pair (which, as fiction, are remarkably better than the others). Other favorites are Nomads, Marauders, and Magicians.
Still other favorites are based not on quality per se, but on fan resonance among aspects of his audience -- Dancer, for example, is popular with woman identifying as slaves.
As in many things -- beauty is in the eye of the beholder.
I always suggest curious people come, read, take what works for you, leave the rest.
But mainly, these are meant to really make you think. Back when this forum was active, Leonidas (and others) would pose situations that brought treasured values in conflict, really making us reach down and get honest and real about our thoughts, lives, natures, and values.
Ideally, that's what to do with the Gor novels. Though it means wading through long repetitive sections.