This is a bad book about dumb things that has missed all the marks that made Harry Potter good. 
 Let me break it down; 
 1. Consistency of the rules established in the previous books? Gone. 
 2. The characters we know as good as we know ourselves? My Immortal-level bad, written with no idea what made them great in the first place. Honestly - Harry would never treat his kid like that. 
 3. The "plot"? A mess that litterally made me facepalm several times and go "thank goodness J.K didn't write this", because then it would litterally have to be canon. This feels like a bad - a very, very bad - fanfiction. Except bad fanfiction would not have queerbaited its readers to go for some dumb copout in the end screaming "totez str8, m8, lol". 
 Yeah, i'm not going to go into details. After writing this, I can finally let this go. If you liked the book and the play? I can totally respect it, but I will never EVER have any positive thoughts about this book (and no, i'm not being blinded by nostalgia or whatever. I know a bad book when I read it), and I will never ever think of this book as anything other than bad, cashgrabbing fanfiction.