According to the novels, Darkover is the only human-habitable of seven planets orbiting a fictional red giant star called Cottman.
Has anyone who has read the books comment on the series?
Well, I certainly haven't read them all. Like most open-ended series, the storylines twisted, the covert narcissism in the character arcs became more and more overt and the themes, such as they were, got completely lost.
Basically it started off with the people of Darkover, who eschewed cowardly long distance weapons in favor of noble and brave hand to hand combat, had developed a society with a noble elite of tepaths etc. The people aren't aliens but a lost colony of Earth by the way. The society had somehow fallen into decay, despite the reality of seemingly magical powers, and was threatened by the inhumane scientific abortion of a culture being forced onto the innocent peoples of Darkover by an arrogant Terran power blind to the true powers of the mind.
Yes, yes, it's all demented but it was at least sincere and at least about something besides cheap thrills of a Leigh Brack/C.L. Moore variety. The women who constantly wore chains connecting their ankles were if I recall perhaps the most notable instance of some of the real appeal of the early series. Bradley apparently was a serious New Ager who really believed this shit, as well as being a little adventurous sexually. I gather for instance she had an open marriage with a gay man, Jon L. Breen, a major figure in the mystery field (albeit mainly as reviewer and anthologist.) No doubt this is an aspect very attractive to the producers who correctly see skin and S&M as a major part of Game of Thrones' popularity.
Later the series veered off into more and more tedious intrigue amongst the magical nobles, delving more and more into backstory. I can't say there was anything particularly sincere and substantive beyond wish fulfilment fantasy.
Re serialized and episodic television, it is crazy to insist that technological factors are responsible for the vogue for serialization. In particular, soap operas were a mainstay of broadcast television for decades, yet the same supposed technological and economic causes promoting serialization in prime time are killing off daytime serials.
Serialization has nothing to do with art, except to make it much harder to make good drama. It exists solely to hook an audience and keep them coming back. Serialization was used in daytime because there was a smaller audience. Housewives had work to do. They had to have a hook to get them to schedule the vacuuming for another time.
Premium cable tends to use serialization because they have smaller audiences and are trying to get a core of viewers who'll pony up the premium. There really isn't any percentage in episodic television because, after all, few people will pay monthly premiums for an occasional episode. Premium cable series are not offering a superior dramatic format. Most premium cable series collapse as dramatically as Dexter precisely because of the open-ended serialization is fundamentally incompatible with quality drama. The cable series do not even offer more imaginative or artistically original fare. The cable series simply offer racier fare that advertisers are still afraid of. Sex and gore are the only things that cable does better, and claims to the contrary are delusional.
Basic cable of course tends to avoid serialization because serials are usually inferior, having less to offer once you know how the story comes out. Which is naturally less popular. Broadcast networks tend to use serialization more today because they are struggling to retain share in a dwindling audience. There is a genuine tendency for serialization to work better in DVD format but there is still formidable competition for serialized programs even there from episodic television. The very worst offenders in episodic television, series from the Fifties, Sixties and Seventies also sell in DVD. And of course, these are often the mainstays of basic cable. The perception that serialization is taking over is an optical illusion caused by an excessively narrow focus.