The book was sort of an encyclopedia, and JK Rowling has taken it to a rumoured 5-movie series expanding the Harry Potter universe. Undoubtedly, the strength of Fantastic Beasts and Where to Find Them, is the creativity in the conceptualisation of these magical beasts, although Eddie Redmayne's portrayal as a bumbling scientist magician (is there even such a thing?) is also notable. The movie plot is basic, and rather mundane - and the whole magic vs humans story-line resembles the X-Men story-line a bit too much. Undoubtedly, other fictional universes have handled the whole human vs magical worlds better - The Nightwatch Series comes to mind; and while the backstory is interesting - this seems far too much like a commercial expansion for the sake of commercialisation rather than expanding the literary world of Harry Potter universe.
