A raw and heartfelt read about depression and growing up.
I saw so much of myself in Tori. I am very much a productive person even in the depths of my depression. Sure I'll alienate my friends and be slugging through everything, but I still show up to school and even an occasional social event. 
I know a lot of people compare this to her later books, but I think there is something deeply personal about reading an author's earlier work, and seeing how much they have really come into themselves as a writer.
I think one of the most interesting aspects of Solitaire is that Tori so clearly reads as being asexual, even though she isn't named as such. While Oseman didn't realise how much she was writing from her own feelings, it was like reading a time capsule of someone struggling with their identity.
If you are trying to read your way through the Osemanverse, I do think this is worth a read.