This is not what I was expecting. This felt like a cross between Harry Potter (age group, framing device of a school year) and the Nightrunner Series by Lynn Flewelling (fantasy realm with students and wizards and such). It didn't have the depth the other two series have, though there's plenty of world-building and a lot of potential for this to grow as the series goes on.
The focus here is on Gibben, a young farmer who's drafted to be a sentinel for the King's Army. Gibben's only thirteen, but he's been in charge of his family of two younger brothers for two years, since older sister volunteered for the army herself, working on their family farm. Leaving for Academy means leaving his brothers alone with the winter coming.
When he arrives at the Academy, he meets a lot of people, lowborn and highborn alike, and makes quite a few impressions along the way. I sometimes felt like Gibben was too naive at times, but he's also a smart young man who makes friends easily. We don't get to see any of Gibben's time in his classes other than his basic training for the army, which felt like a missed opportunity to me, especially since Gib keeps finding himself in situations where those studies would probably come in quite handy.
There were a couple of things that didn't really sit well with me. There is a small scene that borders on sexual assault - it's not followed through and is stopped before it gets anywhere - however as it involved Gib on the receiving end of unwanted attention, it just comes across kind of 1) unnecessary and 2) sleezy. He's thirteen. I get this is a world where 13 = Adulthood(ish), but when the narrative and every single character constantly calls him "boy", scenes like that just feel creepy. His budding romance with a fellow student is at least kept sweet and innocent, but even that I felt could have been held off until the characters age a little more.
One other nitpick is the overuse of epithets: Gib is constantly described as "the sentinel trainee" and his roommate Joel as "the mage trainee". It's pretty much every other paragraph and often in the same paragraph where their names are also being used.
It was a good story and easy to read. I was expecting it to be more on the side of fantasy, but while there are fantasy elements (the mages, mostly) there really isn't much magic encountered or used during the story, as we're following Gib, who is non-magical. I enjoyed seeing Gib's growth over the course of the school year (or, half-year, actually) and his group of friends have a lot of potential. I especially like Kezra. There's also a mystery of sorts to solve.
It's a good start to the series. I will be looking for the next one.