I read all of this in one sitting. It was glorious. I highly recommend you watch the movie first, it is word for word what happened on screen. JK Rowling writes so vividly the movie replays in your head as you read. I give this book (screenplay really) but there is so much detail you can call it a book, 4 stars. I loved this movie better than the HP movies (and I have read all the books and seen all the HP movies) You can see darker themes developing and I would say after reading the book you become more enchanted with the beasts and especially Newt's relationship with them (my favourite is the mooncalves!)
The characters are vived, enchanting, vulnerable and relatable. There is a level of gentle maturity present in this series that was absent in the HP series.
If you loved the movie I highly recommend the screenplay!