In my experience, you can count on Timothy Zahn for three things: clean, sparse prose; good pacing; and great action scenes. The first book in the Cobra War series hits all those marks in admirable style and makes for a quick, entertaining sci-fi novel.
In a far Earth future, a series of colony worlds are defended by Cobras, elite warriors with weapons and other enhancements surgically implanted. It has been years since the last big war with an alien race called the Troft (who, if I'm reading it right, are actually surly turkeys with space guns). In the intervening peace, humanity has lapsed back into a slightly demanding complacency. The Cobras spend most of their time these days hunting spine leopards, space beasties which seem to eat everything on the frontier but the rocks. The troops are also derided as an unnecessary government expense. Into this slightly tense atmosphere comes a mysterious note addressed to one of the most famous soldiers alive, Jasmine "Jin" Moreau.
Not that I've ever had this happen to me, mind you, but if and when I receive a note which begins "To the Demon Warrior," I don't think my first reaction will be to run off to another planet. Then again, I'm not a cybernetic super-soldier. When the unsigned missive slides across a table early in the story, it's clear there is huge meaning in that phrase, but as a newcomer to the series, the nature of that meaning wasn't immediately apparent. Alliance begins a new trilogy, but is actually the fourth Cobra novel. Zahn wrote the original set from '85 to '88, so I think my ignorance can be forgiven. With a twenty year lapse, a little more back-story would have been nice, but that's not really Zahn's style. His focus is the action at hand and moving the story forward, leaving the reader to pick up the scattered crumbs of exposition. In the context of the whole novel, it's relatively minor, but I do think it creates a slightly jarring effect in the early chapters which may be off-putting to some readers. After all, if J.K. Rowling can squeeze in a review after a year-long lapse, I don't think building a bit of a bridge across two decades would have killed anyone.