The voice acting is still top notch and the sound track has seen a lot of improvement as well.
The biggest step up in the game in my opinion. It was a huge weak point in the first game and the sequel rectifies that. It looks great. A few minor bugs but nothing major. Wide variety of environments as well.
Same as the previous game. A bit more defined and sharpened but that's about it. If it ain't broke, Don't fix it. It's still a blast to play.
Much improved story but it takes quite some time to get any good. They go into a lot more detail with the story behind Borderlands as well and that was a huge plus. Handsome Jack is a great villain. The new main characters aren't as fun as the last ones, They are pretty much the first characters in different skins. Even more side missions to play which boosts the replay value. Plenty of awesome easter eggs to find as well. Online play has improved as well. Difficulty curve makes it frustratingly difficult to play through at times, Requires a lot of hours spent grinding out levels in order to advance without issue.
The sore spots of the game would definitely be the difficulty curve and that the story that takes nearly the full game before it gets any good. Aside from that, It's everything you'd want in a sequel. Every thing is a step up from the previous Borderlands.
A worthy sequel