Firstly, this is a series I've been looking forward to reading for a long time. I'm a huge fan of anti-heroes and this sounded like it would go one better and give me a villain perspective to root for. It didn't quite deliver as much as I wanted it to - mostly because the third book felt like a let down to the whole series.
Adelina was such a well written character. She started off damaged and hurting (but yes a little bit brutal) and then over the course of the books she grew so much and it was so much fun to watch. By the end of the first book she has been rejected and betrayed over and over and it finally takes its toll on her, erasing that last bit of "I want to help" that she had in her and forging a self-interest that was extremely compelling to watch. I think I related to this so strongly because I was bullied in school and there were so many times I wanted to turn around and say "screw this" and go full evil queen. I never did (thankfully) and instead took the opposite route but I could have been this. And that's what makes Adelina so compelling. She is a villain we can understand, can get inside of. And that makes her actions so much more disturbing.
Side characters weren't as exciting. Violetta, Adelina's sister, was downright boring for me. She was very much written to be the opposite of Adelina but this wasn't executed in an effective enough way and the tension between them came out of nowhere and then had very little impact on the story. The only side character I grew truly attached to was Magiano (who was an absolute delight) but he wasn't present in the first book and didn't get nearly enough action in the second and third either - he deserved better dammit.
For the most part though the first two books were the villain origin story I've always wanted and if it had been left there I would have been happy. But the third book came along to throw a redemptive arc in there and some truly baffling mythology (that unless I'm super dense wasn't in the rest of the series) and it threw the whole experience off for me. By now it's pretty obvious that I love villains. And I really hoped that this would be my one fully unapologetic villain. But instead Marie Lu explained away Adelina's actions by having them be caused by events outside her control. And then she and all her enemies went on a trip to the underworld that, frankly, I didn't fully understand.
I feel like this was a problem I had with the Legend series as well in that I just do not get on with Lu's endings. I like endings that are one thing or another. Happy or sad. Closed or unclosed. Marie Lu writes endings that are trying to be both happy and sad and closed and unclosed and I just can't wrap my tiny brain around it. I still think this was an excellent series. And I love what the first two books gave me. I'm just going to do my best to forget the third book happened.