I loved Andrew Breitbart personally. I only had positive interactions with the man. I agreed with his worldview. And I think his legacy is mixed for reasons outlined in the following critique. Andrew was often reckless with the truth and needlessly cruel in the pursuit of right-wing causes.
I think Conor Friedersdorf nails it:
It would have been great if the Big sites aimed for higher quality journalism. Said libertarian press critic Jack Shafer in his obituary of Breitbart, “I liked the idea of Andrew Breitbart better than I liked any of his work at Big Government, Big Hollywood, Big Journalism, Big Peace, Breitbart or Breitbart.tv.” And no wonder. What are the best 10 pieces published in the history of those sites? You’ll find more quality work in a single issue of City Journal than the sum total of everything Breitbart wrote or commissioned and published in his whole career. That magazine laid the intellectual foundation for a renaissance of conservative ideas, policy successes, and cultural transformation in New York City — as hostile a territory as there ever has been for the right.