I waffled all over the place with what to rate this book, since the different elements earned vastly different ratings, in my opinion.

World-building: 5 stars. Yes, okay, I was a /liiiittle/ disappointed to see ANOTHER magic school, but overall the different kinds of magics, the caste system of magic-wielders as /servants/, and the Russian folktale inspired setting, had me invested.

Themes: 4 stars. A little on the nose, but I found them important themes that a YA audience might need or seek to help deal with real life trauma. There is the obvious theme of Darkness and Light (Greed and Mercy/Selflessness) keeping each other in check, which was represented physically in some beautiful magical moments between The Darkling and Alina. But there's a second story being told about rape culture, and how this one girl learns she has the strength not only to not depend on a man, but to confront people who seek to use and abuse her. She has a very literal inner light/strength.

Plot: 3 stars. Things seem to just clunk into place because people say so. One day, Alina is revealed to be a Sun Summoner, because The Darkling says so, and now that's all she wants in life is to be a Sun Summoner! Another day, Marie and Nadia are her friends now, because they say so! Another day, Alina's powers get stronger, and she has no more nightmares, and she has an appetite, because... she decided to! And she and The Darkling talk maybe twice about vapid nothings, how was school, how's your day, ho hum... until they're kissing hungrily and begging for more, because this is a romance now, we say so! And then The Darkling is evil, because Baghra says so! And much much later Alina overcomes slavery... you guessed it, because she said so!
Long, spoilery rant, short: I didn't always feel that the plot points were earned. Things were abrupt, forced, sometimes awkward, like they were only included to satisfy a YA Bingo card...

Romance and Characterization: 2 stars. Oof, yeah this is the heavy hitter that dragged this book down for me. Obviously, The Darkling is controlling and abusive, but even before the midway reveal of his schemes, I wasn't feeling him as a love interest. He was A) In a position of power over Alina, like a schoolteacher, with 100+ years on her. So, right there, grooming. And B) The Darkling and Alina shared very few scenes before their first kiss, there was not a lot of foundation laid.
But Mal was no better for her. Mal had no interest in Alina until she was in the clutches of another man; defined her value in relation to him (ex. I am good man if I take care of you, and bad man if I let you take care of yourself. Ergo, I love you when you need me?), and was brutally judgmental and condescending of everything from Alina enjoying magic school (yeah, who wouldn't, they have champagne here!) to NEEDING TO EAT!!! Spoiler alert ladies, if the "partner" in your life criticizes what you eat, RUN!! Mal played blame-the-victim, too, guilting Alina for appreciating The Darkling's generosity and attention (because, wah, he saw her first. And ownership is nine tenths of the romance, right folks?), and even going so far as to FORGIVE her for being wooed by The Darkling. Forgive her? Forgive her?! She wasn't Mal's fiancee, or girlfriend, or anything. She owed Mal nothing more than friendship, which she continued to give even as he was terse with her. Grow up, Mal! If you like it, then you shoulda put a ring on it!
But... *sigh*... I'm sorry, Shadow and Bone fans, I didn't like Alina either :/. She was sulky and self-deprecating, and constantly looking for a man to be with or a man to validate her place in the world... She was a weak sauce heroine. I know, her big strength is supposed to be her kindness, and hey, some girls identify with that. You do you. I didn't find Fluttershy the Sun Witch compelling. In fact, by the end, I was actively rooting for her to lose something important, so that she could have a turning point and become wicked.
Circling back to The Darkling... am I missing something here? I feel like I must be too Slytherin to follow this plot... because The Darkling doesn't sound like the bad guy to me. In fact, his plan seems pretty darn reasonable. A bunch of neighboring countries have been at war for a century, the border countries actively killing off wizards, while the central country keeps them as slaves or soldiers. The Darkling's plan is to use magic to spook the bloodthirsty muggles into leaving the wizards well enough alone, thus ending the war, and lifting wizard-kind from enslavement... How is this a bad thing?!?!? (Yes, I know he destroys his own townspeople with dark magic. I didn't say that he was perfectly written, only that his rebellion makes sense.) I don't understand why we're rooting for Alina to keep status quo, instead of for The Darkling to lead a coup. The King is a rapist, The Queen is a lazy diva, wizards are slaves, people are dying... Yeah, time for some new management. Go Darkness.
Honestly, the best character in the book was Genya. She was sassy, damaged, literally hiding her emotional scars behind a magical glamour mask... Every time Genya was mentioned, it was always "beautiful Genya", and given Alina's obsession with Genya's beauty, I reeeeeally thought this was going to turn into a lesbian love story. How fantastic would that have been! In a story where the theme was /trying/ to be, "Girls, you don't need no man!"... YES, show us a protagonist who doesn't need a man! I was heavily invested in the camaraderie between these two. I felt the story got bogged down when Genya was given a crush on a background, male character, and Alina went hiking for days with Mal... Imagine if they had begun to fall for one another, before Alina had to flee, and when they were reunited... Genya's betrayal, her red robes, her politicking to gain power, would have hit as an even deeper betrayal: Alina who believes you can beat the system by being kind, and Genya who believes your only choice is to play the system and be more ruthless/cunning than everybody else! Bwahaha! Will they reconcile in the sequel?! Stay tuned! That story would have had my attention. Alina waffling between two hot guys who are mean to her while she is mean to herself for 350 pages... did... not...

All in all, I'm hopeful this is just a bumpy start, and the remaining Grishaverse books kick it up a notch. (I mean, hey, Sorcerer's Stone isn't the best of the Harry Potter books, but you have to introduce your world somewhere!) We'll see :/.