While hailing Diego Simeone as a "great coach", former Real Madrid striker Ronaldo said he is not a fan of the Atletico Madrid boss' tactics.
Simeone is preparing to lead Atletico into their second Champions League final in three seasons, with city rivals Real Madrid standing in their way of a maiden title in Milan on Saturday.
The Argentinian has become one of the world's most sought after coaches since helping Atletico to La Liga glory in 2014, the club's first top-flight crown in 18 years.
But ex-Brazil international and three-time World Player of the Year Ronaldo, who played alongside Simeone at Inter, is not completely impressed with the 46-year-old and his brand of football.
"I am in love with football that is played well," Ronaldo told La Gazzetta dello Sport.
"Simeone has an Argentinian temper and transmits that to his players. Things that I do not [personally] like, but he is a great coach.
"His team plays well, they are tight and compact. They have their own style and are difficult to deal with."
Simeone has talked up a return to Inter in the future, having won the UEFA Cup - now known as the Europa League - in 1997-98.
Asked about Simeone going back to Milan, Ronaldo added: "I think that sooner or later he will go back.
"I have said that many times because he is very close with the club."