Roger Ebert said a lot of things I would disagree with him on. He liked a different type of movie than I did. But...
I will maintain he is important to films. He made the film review something that could be entertaining on its own. He made 'knowing things about films' something interesting. And if it weren't for Roger Ebert, I wouldn't have all the beloved internet reviewers I love to watch. Atop The Fourth Wall, The Cinema Snob, Nostalgia Critic, SF Debris. Reviews are entertainment, and that is one thing that he brought forward.
He made you think about movies. Even if, sometimes, all you thought about was how Roger Ebert was so totally wrong, he still made you think.
Yes, he said videogames aren't art. Quite honestly, I never understood caring about it. He's a film guy. He says film is better than videogames. WELL HE'S A FREAKING FILM GUY.