Really, really good, but not sure he makes the top 5 DUKE players (in college) over teh last however many years. Laetner was a GREAT college player--incredibly unlikeable for non Duke people, but arguable since the Alcinder and Walton days he had the best college career of anyone, Hurley is in the discussion as the best college PG in a long time, Grant Hill was special, then you get the to Banchero's, Flagg's, Dunleavey's, Brand's, Williams's etc.
That said, he has better numbers that several listed, but he also has more freedom than several, and the competition he is facing is less than several mentioned because the ACC is so bad.
All that said, he is really fun to watch, and for the age--just turning 18--he is incredible. If I am OKC, this may be the year I push in the chips with my draft capital to move up and grab him to pair with Chet and SGA