These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Bizarro Episode: The sixth and final book deviates heavily from the rest of the series, being mostly told from a first-person perspective, and featuring aliens, time travel, and alternate universes.
Darkness-Induced Audience Apathy: In the fourth book, Sparta and Blake are separated, and Sparta all but burns her bridges with the Space Board, then gets hooked on drugs, murders a bunch of people, attempts to sabotage a Space Board mission, and ultimately suffers a nervous breakdown. Paul Preuss himself conceded that he feared many readers would abandon the series after reading it.
Fanservice: The series has nude scenes and sex scenes throughout, but the fifth book really takes the cake; Towards the end, Sparta abandons her clothes and spends the rest of the book swimming nude around the world-ship.
Les Yay: The second book opens with Sparta receiving a massage from another woman.
Moral Event Horizon: Ari Nagy, Sparta's mother, willingly handed her own daughter over to the Free Spirit cult, and unlike her husband Jozsef, she's not sorry. On top of that, she let her daughter believe that the Free Spirit had killed her and Jozsef, resulting in Sparta nearly throwing her life away on a poorly-planned vendetta.
Strangled by the Red String: Sparta and Blake's relationship is more told than shown, and relies heavily upon the notion that constantly rescuing someone inevitably results in them falling in love with you.
Tear Jerker: Kara Antreen's fate at the end of the first book; She ends up with her memories thoroughly wiped by Sparta.
True Art Is Angsty: The fourth book features Sparta breaking her ties with the Space Board, getting hooked on drugs, killing a bunch of people, attempting to sabotage a Space Board operation, and suffering a nervous breakdown and temporarily losing her enhanced vision. Preuss has justified all this, saying that character development requires confronting despair and figuring out a way past it.