The biggest weakness in Horizons is the lack of character development, which is made only more apparent by the great possibilities inherent in the majority of her primary characters. Ahni, Dane, Li Zhen, Laif, Noah... all have the potential to cross the threshold from stock character to interesting person, but for whatever reason the author chooses not to pursue that path. Unfortunately, the effect is not as winning as that of other, what I would consider to be similar, novels such as Vinge's Marooned in Realtime or McDevitt's Seeker.
Primarily an action-hero novel, Horizons - other than brief interludes discussing hydroponics and rock-smuggling - avoids discussing anything of any real substance. The driving motivations for the characters are muddled, muddied, and vague, from politics and independence to evolution. The evolutionary position she takes could possibly be interesting, except that for some reason she breaks the cardinal rule of "show, don't tell" - rather than allowing the main character, Ahni, to discover the truth herself, the author has Dane simply tell her the answer to what could have, and probably should have been, the largest mystery of the novel. Instead, the entire effort is reduced to just another "whodunnit", and even that is not done very well, with the reader having no reason to suspect the suprise villains revealed only at the very end of the novel.
Thematically, Rosenblum does not seem to have anything really strong or important to say beyond the mixed messages already discussed above. The novel works, but only as a quick, light read, and I would actually recommend others in this vein (Marooned in Realtime, Seeker) ahead of Rosenblum's attempt.
