It got back the charm, tone, and dynamic that it had during the first season, and made leaps and bounds as far as relationships (note especially Addison/Miranda and Addison/Meredith). And high!Meredith is just about the best thing since sliced bread.
(By the way, why have we not discovered anything better than sliced bread? I mean, yeah, I don't want to cut up a whole loaf myself...but is unsliced bread really that bad? I'd say that the automobile, the airplane, the internet...these things are all better than sliced bread.)
And now, CSI!