Jonathan Chait said many of the things I intended to write about Andrew Sullivan's blog, only he said them better than I would have (as he so often does). I'll add just one thought.
Andrew was no longer editor when I arrived at the New Republic in 1997, so I knew him only from his written work. And, to be honest, I was not such a fan. Yes, he was a brilliant writer. But he was too much of a provocateur for my taste--somebody who seemed to relish outrageousness for the sake of outrageousness.
Then I got to know Andrew a little bit. And I came to appreciate what I suspect most Daily Dish readers already know: Andrew simply has an uniquely aggressive mind. He genuinely enjoys challenging what other people think, even when that means challenging himself.
That's what makes his blog such a bracing and illuminating read: You get to see this intellectual process as it is taking place. (And, at least in my case, you find yourself asking questions you didn't think to ask before.) I mean no disrespect when I say it's frequently more interesting than the result, because you never know how it will unfold.
At the risk of sounding like a curmudgeon, I think very few writers on the internet are nearly as interesting as they seem to think. Andrew is one of the exceptions--and a model for the rest of us trying to follow in his footsteps.