The middle book in any trilogy is always problematical. The author has to make the situation worse-and-worse for the protagonist, yet move the story forward. Yet, very little can be resolved, because there's a Book 3 to follow.
Kritzer does a great job. In the first book of this trilogy (don't even think of skipping it; you'd be lost), Lauria re-thought her role in the world. Instead of doing whatever Kyros wanted (in particular, catching slaves and returning them to their owners), she joined a peculiar rebellion, and earned a sense of purpose. (I won't say more, in case you didn't finish Freedom's Gate yet.)
In Freedom's Apprentice, Lauria aims to free all the slaves she'd previously recaptured, as atonement for her previous actions. As she travels around her world -- joined by her blood-sister Tamar -- she learns more about the nature of magic, what it takes to control it, and sets an even larger goal.
Oh dear, that sounds like the vague "back of the book" text, but I'm trying to avoid spoilers. The bottom line is that this second book is at least as good as the first; the author makes her world and her people believeable; and this tale is a fine place in which to lose yourself for a few hours. Recommended.