There are many cuts that disappoint me, not just Oliver. The twins play such a great part in the books, but you hardly see them in the movie. And you don’t see enough of the professors, either, IMO.
I won’t reveal any spoilers, but those who have read the last book will know who I mean. Helen Mirren would make a great “bad guy” later on. Helena Bonham Carter would be a good casting for the good witch and Amanda Donohoe would be great as one of the big evils that comes up later. All MHO, of course.