3.5 Stars 
 Suggested Subtitle: Levana's Journey from Malignant Narcissist to Raging Sociopath. 
 To be completely honest... I went into this series tie-in not expecting to like it. Some people love to indulge in extended villain backstory. I am not, typically, one of those people. I do, however, appreciate an interesting character study. And while you have a pretty clear idea of how badly this particular story does and must end, there are enough peripheral characters and curiosities to keep fans of the series captivated throughout most of the telling. (Not to mention some relevant background that Cinder simply can't remember.) 
 Levana isn't a basically good or sympathetic character who just made a few mistakes, or who well-meaningly got behind the wrong cause. She instead represents the perfect storm of nature vs. nurture. While there's some effort to make her seem sympathetic initially, her warped and forceful desire to make herself happy--at the expense of all else--proves caustic to those around her and to the tiny shreds of human empathy she may have been capable of. The most this reader could ever feel was a sort of foreboding pity toward one so willfully incapable of comprehending love. 
 But while I can't say I enjoyed the experience or content, it did keep me engaged enough to motivate my reading onward the entire time. Meyer has really come into a smooth, comfortable prose that makes for easy reading. The story could almost stand alone, but will work far better as a supplement to those "Lunartics" who are already well into the series. 
 The most insightful (and perhaps valuable) takeaway for teen readers may be in having this opportunity to watch the gradual transition from simple selfishness to unmitigated evil--as Levana steadily and intentionally kills off the shriveled, immature part of her that could have passed for a conscience. She does so quite believably by first indulging in vile thoughts and fantasies, and then gradually beginning to act on said fantasies. The psychology of those reinforcing thoughts and decisions ring devastatingly true--even far outside of fairy tales. 
 A universal truth is successfully conveyed. Absolute power corrupts--not all at once, but a little at a time. And it isn't merely morality that it corrodes, but sanity as well. 
 Still, the biggest issue I had to take with this story was the timing of Levana's last dastardly deed. All of her decisions up until that point had been fairly logical. Cold, self-centric, and amoral; but still calculatingly logical. Without spoiling the actual incident for anyone, I'll just say that she puts herself at an emotional disadvantage YEARS before the move would technically be necessary as her intended means to an end. 
 All in all, a quick and series-enhancing read. Worth the time investment for existing fans.