Well, there are a lot of things I would like to say about this book. Some are positive, some are negative, but I gave it 5 stars, because, even though I expected it, I didn't see the word 'kiss' in it, which pleased me a lot. 
 Positive: 
 1. I loved the Harry Potter references. May be some people would find it stupid, but I loved the ''Thank you, Professor Dumbledore" thing. 
 2. I liked all of the characters. They felt real, with personalities, likes and dislikes, and even throughout the novel, you could predict their actions, which only made them more real. 
 3. I liked the story, the way the POV shifted to the victims(we don't see a lot of that in YA novels) the mystery and the clues was all perfectly made. 
 4. As I mentioned before, the fact that even though we see a little chemistry between the characters,there isn't any actual romance, which is a relief, really, for a moment I thought that we were going to be shown a love triangle here, but, fortunately, it's left for the rest of the books in these series. 
 Negative: 
 1. The fact that the plot wasn't completely solved. I know that the writer needed material for the rest of the books in these series, but, still. I wish it did, and we would get to see some new adventures. 
 2. The fact that Doctor Ambrosius was an unreliable character. I mean, you turn them into mice the first time you meet them, and than, you can barely remember the names? Not cool whatsoever. I wish Spirit could rely on him at least. 
 3. I know it is supposed to be something big, but I wish Spirit had her own magic discovered in this book. But I guess, I will have to wait for that. 
 Though there are similarities to Harry Potter, I still liked it. It has become one of my favorites,and I truly hope I will not be disappointed with the next installment.