If people lived much longer lives, the rate of civilization's progress would probably slow way down. There wouldn't be any time pressure to do great deeds - one could just decide to do them in the next century, "when I get tired of surfing in Hawaii". In the other hand, people would have more time to learn how to do things right, and great minds could continue their work, which might get exponentially better as they reach 200, 300, or 400 years old.
Society would run into an ugly problem: we need the Einsteins to live for thousands of years, but we would prefer that Earl the janitor get out of the way in about seventy, to avoid stressing social welfare systems and because, frankly, Earl just doesn't contribute much. I expect access to the therapies that extend life will be limited to those who can pay a huge price for them or those the government deems worthy of an "extension grant".
I agree with most of that (except there probably won't be an 'Earl the janitor'—robots, you know).