2.5 Stars 
 This book isn't so much about the title character--or at least, it is much less so than the first three primary books in this sci-fantasy series of fairy tale retellings. 
 Unfortunately princess Winter is just kind of... there. All helpless and victimized--partially by her own refusal to exercise her "gift," despite there not being a strong moral argument against it. In essence, she could have avoided her clearly detrimental and ally-endangering "madness" by using her Lunar gift to, say, innocuously make people think her nail polish was blue instead of red. But she's such a legalistic stickler for her I-don't-want-to-be-like-my-stepmother principals, she would rather be a mentally ill liability than in any way accommodate the biological needs she can't help having. 
 The romance is kind of a given with little development--as it utilizes the 'childhood-friends-turned-lovers' trope. Ordinarily I like that kind of pre-establish familiarity, but due to Winter's self-imposed "condition," the romantic angle was made complicated and questionable by the caretaker/mentally-compromised patient relationship. 
 Also, it felt like a LOT of issues could have been avoided and lives saved if Cinder had just spent her copious amount of time in hidden orbit programming Iko to be a sharp-shooter assassin droid. Iko proves to be a decent fighter, but given she and Cress are the only ones who aren't affected by Lunar mind control... stuff... it would have made perfect tactical sense to weaponize her. 
 I'm fairly certain our heroes would have had no chance at all if Levana didn't keep violating so many Evil Overlord rules. 
 (Yes, I actually kept track of them. No, I don't consider the following to be spoilers. If you do--feel free to skip!) 
 #4. Shooting is not too good for my enemies. 
 #6. I will not gloat over my enemies' predicament before killing them. 
 #39. If I absolutely must ride into battle, I will certainly not ride at the forefront of my Legions of Terror, nor will I seek out my opposite number among his army." 
 #48. I will treat any beast which I control through magic or technology with respect and kindness. Thus if the control is ever broken, it will not immediately come after me for revenge. 
 #61. If my advisors ask "Why are you risking everything on such a mad scheme?", I will not proceed until I have a response that satisfies them. 
 #64. I will see a competent psychiatrist and get cured of all extremely unusual phobias and bizarre compulsive habits which could prove to be a disadvantage. 
 #67. No matter how many shorts we have in the system, my guards will be instructed to treat every surveillance camera malfunction as a full-scale emergency. 
 #71. If I decide to test a lieutenant's loyalty and see if he/she should be made a trusted lieutenant, I will have a crack squad of marksmen standing by in case the answer is no. 
 #103. I will make it clear that I do know the meaning of the word "mercy"; I simply choose not show them any. 
 #104. My undercover agents will not have tattoos identifying them as members of my organization, nor will they be required to wear military boots or adhere to any other dress codes. 
 #106. If my supreme command center comes under attack, I will immediately flee to safety in my prepared escape pod and direct the defenses from there. I will not wait until the troops break into my inner sanctum to attempt this. 
 #151. If I make a zombie out of one of the heroes, rather than killing him, I will not put him in a position where he will make ANY contact with his friends, lest he remember them and turn against me. 
 Personally, it drove this reader up a wall to keep hearing terms like "intergalactic," yet having no indication that humans in this book's world have expanded out beyond even their own moon in colonization. No other part of even the immediate solar system is mentioned in any of the books, as far as I can recall... (Please correct me if I missed something.) 
 I don't doubt this was a difficult book to pull together. I have to applaud the effort that went into tying up long established storylines and juggling the romantic arc of four significantly different couples. (It was particularly nice to see Cress' story receive a little more attention and closure.) The characterization remained consistent--as did the upper middle-grade tone. It just felt like the overall work suffered from too much going on and a conveniently dragged out conflict.