George Clooney has a "huge heart" and is "incredibly loyal".
The 'Monuments Men' star has been good friends with Matt Damon for a long time and the 'Martian' actor has praised his pal for being "really smart" and talented.
He said: "Sure, he's changed. He's evolved, but he's the same in a lot of critical ways. In all the important ways, he's the same; he's got a huge heart, he's incredibly loyal, and he's really, really smart.
"He's changed his career, in a way. When I met him, he was just coming off ER; he was known as this massive TV star. People didn't understand how talented he was; they just thought he was this really handsome, matinee-idol TV star."
And Matt likes to go to George for advice as he "really values" his opinion.
He told the Hollywood Reporter magazine: "Now the perception of George is as big a movie star as you can get, an A-list director, an Oscar-winning producer. He's somebody whose opinion I really value.
"If I'm working on a script, I'm sending it to him for notes; if I'm doing a movie I'm showing him a cut and asking for suggestions. In baseball, they would call it a five-tool athlete - just somebody who can do everything. He's an easy guy to hate, I guess!"
And it shows how close they are as Matt previously admitted to "almost crying" when he found out that George and Amal were going to be welcoming twins.
He said: "I was working with him last fall and he pulled me aside on set and I mean, I almost started crying. I was so happy for him. And I was like, 'How far along is she?' And he goes, 'Eight weeks.'"