[MILD SPOILERS ALERT !!!] Unfortunately an utter disappointment. The character of Addie was so underdeveloped that I basically didn't care at all about her. I just couldn't believe that she was over 300 years old because, the way her dialogues and thoughts were depicted, it was missing the kind of maturity and wisdom I expected a 300-year-old to have. Henry was adorable, but I wanted her to explore other important characters as well like Luc or her father or Remy. Unfortunately(again) we didn't get much of either of them.
The fact that she totally freaked out when she first discovered about her curse was totally acceptable. But after a couple of centuries I expected her to come in terms with it ( which she said she did but I don't believe her) and finally pursue things she always wanted to do, after all, she traded her soul for it. That was the whole point of the curse. But she hardly did anything she claimed she wanted to do.
Further, the plot felt really forced and loose at points. For example: according to the curse she was to heal from all the damages caused to her body. So theoretically when she first bedded a guy that was after she became an immortal. So she should have remained a virgin. But according to the reactions of other boys she slept with, I don't think that was the case. Another thing that really bothered me is if she was so unhappy with her curse, the first thing I expected her to do was to do something to undo the curse. Call on other Gods most probably or try contacting any other witches like Estelle but she did absolutely nothing about it.
Talking about the positive aspect, the idea behind it was really good. I loved how Schwab interpreted Addie's freckles( her own little constellation) The writing style was actually good and quite lyrical, but when you start hating a book that lyricality becomes very irritating after a while. I liked the ending and the beginning both, the rest was just "meh". So overall it wasn't a terrible book. You can yourself give it a try and see if it works for you.