Ann Aguirre's debut is another space opera-cum-romance, which means if you're a reader likely to squee over that kind of thing, notch the rating upward, while those of you who would rather have bamboo shoots under your toenails won't find a lot here to disabuse you of your distaste. Sirantha Jax is a navigator working for the Farwan Corporation, a.k.a. The Corp, one of those faceless monolithic entities that tend to serve as the all-purpose metavillain — here representing the evils of monopolistic governmental bureaucracies and unchecked capitalist greed — in stories like these.
Aguirre's clever idea here is that of Sirantha's profession, a jumper. Far different from Steven Gould's concept, Sirantha works in tandem with a starship pilot by virtue of a genetic mutation that helps her guide the vessel through "grimspace," which is Aguirre's variant on hyperspace, or whatever extra-universal reality SF writers like to imagine ships go to in order to cheat the speed of light. The problem with being a jumper is that the experience of jumping has a narcotic effect quite like a heroin rush. Coming down is hard, and jumpers tend to have brief careers before they burn out. Sirantha has lasted longer than most.
As the novel opens, Sirantha is jailed by the Corp, which has accused her of causing a crash that left her pilot/lover and dozens of VIP passengers dead. It's made clear that she's being set up and that the Corp is Up To Something, because evil faceless corporations always are. But she is sprung from her cell by March, who has been hired by interests on an outlying world intent on training up their own jumpers and cutting into the Corp's monopoly, and who want the secret of Sirantha's longevity.
Aguirre makes all the expected newb mistakes in her early chapters. Either the Corp isn't as badass as Aguirre wants us to believe, or it's a whopping case of author's convenience, but we're never satisfactorily told how March and his crew managed so easily to fly into the station where she's being held, bypass all the AI security, and get her out with only token resistance from the "grey men," the Corp's armed guards, whose function here isn't much different from the NPC's in first-person shooters who exist to be mown down. (March has some kind of all-purpose codebreaker, but that's it.) And Sirantha, at first, has all the de rigeur character quirks you expect from space opera heroines these days, chief among which are a chip on her shoulder the size of the Death Star and a big old Attitude where a personality should be.
But once the story gets past the obligatory firefights and whatnot, things settle in and Aguirre allows you time to warm to the characters. Yes, the inevitable love story between March and Sirantha blossoms more or less in accordance with romance formula. But Aguirre gradually transforms Sirantha from a cliché into a person by having most of the story concern itself with her personal journey, presenting her with a character arc in which she learns to accept that there's a big universe of responsibility outside of the tiny one of self-pity she's chosen to inhabit.
I also kind of enjoyed the way in which every single plan March and his crew make towards fulfilling their mission goes completely FUBAR, no matter what. While the Dark Secret of what really caused Sirantha's crash has such an obvious resolution that the only readers who won't predict it halfway through the book will be those who've never read anything before in their lives, I didn't foresee many of the loopy but, on the whole, logically sound (given our two protagonists' tendencies to make really rash and impulsive choices) detours the plot took. The ending is a little too pat to be true. But given that Aguirre has seen fit to populate her book with a bunch of thoroughly neurotic screwups, and then make their flaws sufficiently human and endearing so that their piling-up of one epic fail after another actually earns your sympathy, then I'd say overall, Grimspace manages to inch its way slightly above the grim space of the mass market midlist, and presages the arrival of a writer with promise.