I love the backstory we're given on Byakuya's past here - sad, conflicted, emotional yet somehow emotionless, just like his character. It's my favorite flashback, and it tells us so much about Byakuya, the Kuchiki family and Rukia's own place in the world, more solid than she had previously thought.
I also adore Isshin, Ichigo's father. It's a really great twist and explains a little bit about Ichigo's previously inexplicable powers. I can't imagine how hard it would be for a former Shinigami captain to be unable to protect his wife from a Hollow, nor how satisfying it would be to cut down that Hollow just when it thought it had reached a peak of power. And to see Isshin go from lovable, violent crazy-dad to violent, powerful, intelligent shinigami is really cool. The reveal for Ishida's dad is a little less dramatic, but also interesting.
It was kind of a shock to go directly from the ryoka return to the real world to the Vizard appearance. In the anime this is spaced out considerably with the introduction of several new filler plotlines such as the Bount. I definitely prefer the tighter story that the manga follows. In the anime, it seems like there ought to be a shuttle bus between Soul Society and the real world with how much people bounce back and forth. In the manga their worlds are much more tightly defined, and it's much rarer for people to travel between the worlds.