I thought Terminator 2 did a good job of introducing a new villain in the T-1000, and making the original Terminator into an anti-hero. Even though it was a sequel, it introduced new story elements without rehashing plot ideas from the original. I thought Linda Hamilton did a great job of making Sarah Connor a believable kick-ass mom that was also a little bit psychotic. Not too sure about Edward Furlong's acting, but it didn't detract too much from the sequel.
Very rarely does a sequal outshine it's predecessor, but Terminator 2 is a prime example. Not only did audiences enjoy Arnold Schwarzenegger's change from villain to hero but the introduction of a more dangerous, shape shifting cyborg thrilled and wowed us. Terminator simply set the stage for the impressive movie that is Terminator 2.
Terminator 2 takes up the story again in a really authentic way. This film evolves Sarah's character and gives viewers a great story. It's well-acted and not at all predictable. While many sequels are simple money grabs, this one definitely justifies its existence through great characters, an interesting plot and great action.
Let me say that like the Alien franchise comparing the original Terminator to the sequels is inequitable, apples and oranges dudes and dudets. The tones are very different, the atmosphere, budget, expectation all very different. I enjoyed both movies equally yet for very different reasons. If we go for replay value then the original wins, I even have the original music on vinyl that how much it impressed on me.
Terminator 2 is basically just a remake of the first film. the original plot element- the miles Dyson stuff- contradicts part 1. If Judgment Day is stopped, and the terminators never come about, then there's no reason for Kyle Reese to go back...thus, John Connor is never born. Part 1 presents a closed time loop. Terminator 2 contradicts this by suggesting that the timeline can be changed. This is why I don't regard it as highly as part one. 2nd's a kids' movie.