Point taken when you say it's only used as a mirror... but he doesn't hate it. He both dislikes it and likes it. This is FTA:

"The hosting of github is excellent," he said. "They've done a good job on that. I think GitHub should be commended enormously for making open source project hosting so easy."

But then he listed a few other things he doesn't like about GitHub, including "the way you can clone a [code repository], make changes on the web, and write total crap commit messages, without GitHub in any way making sure that the end result looks good."