What's so terrible about it?

I wouldn't worry about the Medved judgement. He was a novelty book writer of the school that thinks its cool to say clever and snarky things about films that have no defenders. Its not the quality of the film but the opportunity to write amusingly about it that determines what's "worst". Its not a coincidence that his brother has ridden his association with his brother's books to a career reviewing films using a right wing political bias so its no doubt that is why they consider Ivan the Terrible among the "worst". They also called composer Vernon Duke a "hack" (article on Goldwyn Follies). Neither of the Medved brother has a background in cinema studies but they sort of backed into it with their novelty books.

I really liked it. Dunaway & Mastroianni are gorgeous and had lots of chemistry. Dunaway's wardrobe, the sets and Italian scenery are fabulous. The story itself is good: very sweet & sentimental. Wonderful soundtrack, with Ella Fitzgerald singing the theme song. It's unfair & wrong that someone deemed to include this film among ""The Fifty Worst Films of All Time".