I limited myself to one DVD per day. The box sets total 36 episodes spread over 10 disks, with the last disk of BotS2 having a bonus episode that takes place some 19 years before the first episode of CotS.
The entire series is based on a series of SF novels written by Hiroyuki Morioka. (I have heard tell that these novels are available in English, but I have not yet sought them out.)
CotS is 13 episodes long and encompasses the entire story contained in Morioka's novel of the same title.
BotS is 13 episodes long, and encompasses the first third of the novel of the same name; BotS2 is 10 episodes and covers the second third of the novel. (One would presume there is a third BotS series in the works. Good Lord, I hope so. I need more of this stuff.)
The series surrounds two main characters. One is a terran human named Jinto; the other is a young woman named Lafiel. Lafiel is an Abh.
The Abh are a genetically engineered subrace of humans, optimized for life in space. Besides a longer lifespan and unique hair coloration, they also have a sense organ which gives them an intuitive grasp of spatial relationships. Their reflexes are somewhat better than terran human reflexes, as well. The Abh Humankind Empire has dedicated itself to the control of space; they don't care what happens on the planets.
I can't really describe the plot in any great detail without spoilers, so I won't; but I won't give much away if I say that the series is about this pair of humans and their relationship, set against the backdrop of a massive interstellar war.
I've always been something of an elitist when it comes to science fiction. I enjoy all kinds of speculative fiction but I really enjoy the stuff which sticks to the known laws of physics...and when it doesn't, at least makes plausible departures from them.
So, when I say that CotS et al are "good science fiction", it's a compliment.
The story is not about the spaceships or the other hardware. It's about people--and ultimately, the most successful SF is about people, not about the junk that surrounds them. The plot is character-driven; the characters don't "tech" their way out of problems by cross-connecting the replicators to the deflector dish in order to.... The troubles they find themselves in rarely result from mechanical failures; and the few times they do, solving the mechanical failures does not form the bulk of the resolution of the situation.
There are some situations which don't seem to make sense, on the surface, until one looks a bit deeper. In CotS, Jinto and Lafiel must make an emergency landing on a planet; it is Lafiel's first time groundside. (She sees the stars twinkling and thinks she is going blind, until Jinto tells her that the stars do that when seen through atmosphere.) After they have been on the planet a little while, Jinto tells her she must dye her hair black, and she protests.
This seems to jar with a scene from an earlier episode, in which she kills another Abh and coldly cites the necessity of the action: he was trying to kill them, and she did the only thing she could. But an episode or two later, she is unwilling to dye her hair, when it is clearly necessary to their survival. Why?
Ultimately, it is because she is out of her element: when she killed the other Abh, she was flying an Abh ship, in space. By the time she refused to dye her hair, she has been on a planet for more than 12 hours. Far outside of her element, she has been forced to sleep on the ground, eliminate bodily waste outdoors, and--worst of all!--she has had to follow Jinto's direction. Her refusal to dye her hair is a kind of protest, a desire to retain some control over her situation.
What must a space-borne woman have thought the first time she felt wind in her hair? Her instincts should have screamed air leak! at her....
In BotS2 we see, several times, the image of a Dyson Sphere. The Abh capital of Lakfakalle is an enormous space colony; the sun at the center of that system has a sort of geodesic sphere around it, relatively close to the surface. Further out is an enormous network of habitats, all chlorophyll green.
(Note: a Dyson Sphere need not be a solid sphere. That's the most dramatic and, frankly, nifty visual, but it's not strictly necessary that it be solid. In fact, the structure shown in BotS2 doesn't actually meet the test, since it doesn't capture all the star's light, but there may be other considerations. Besides, their plants need sunlight to grow. But it has to be some kind of power plant, or at least contain some kind of power generation system. Heck, it could easily be a way to prevent solar flares, or even a propulsion system...and come to think of it, those two things are not mutually exclusive.)
For faster-than-light travel, Morioka resorts to using gates into "Plane Space". These gates are (I gather from the beginning of the series) some kind of wormhole made using matter with imaginary mass. Robert Forward wrote an entire book around the concept, Timemaster , in which the discovery of matter with negative mass opened the path to the stars.
A gate into Plane Space is referred to as a "Sord"; there are an unspecified (large) number of Sords, they are choke points for interstellar commerce. Every inhabited system has at least one Sord, and it's implied that Sords can be moved.
In Plane Space, a ship must generate a space-time bubble or be destroyed. The ships use antimatter fuel, and much of the fighting is done with a combination of nuclear-tipped mines and missiles, and directed energy weapons.
One interesting result of the physics of Plane Space is that ships which are fighting will usually fuse their space-time bubbles; and the space-time bubble of the victor will collect the shrapnel and wreckage left behind after the battle. Sometimes it's enough to slow a ship down.
Overall, I heartily recommend the series to anyone who enjoys a good SF show. CotS is currently selling for around $30, which is a bargain. The two BotS are going to drop into that neighborhood before too long; BotS is scheduled to drop from its current $45 price to $30 on May 9 as I recall.