Obvious spoilers about Terminator/Terminator 2 in this post.
When the movie came out, marketing had basically plastered the fact that the T101 (Arnie) was a "good guy" in the second movie. I actually have not known anyone to have seen that movie and not realize that Arnie was the "Good Guy". In fact, when I was first married I made my wife watch those movies and she was surprised that he was a "Bad Guy" in the first one.
So last week I finally watched Terminator with my son and he really liked it. Last night we watched T2. I had not told him anything about it except that this time a terminator is sent back from the future to kill John.. The movie is very much designed to have the Terminator reveal be a twist. The T1000 is not shown to be a terminator, or to kill anyone, and the T101 is just being a T101. (Give me your boots and jacket etc).
The showdown at the mall in the hallway was perfect and Arnie finally says "Get down" and starts shooting the T1000. My son yells out "HE'S the GOOD GUY?". It was fantastic and I realized how much that this is the ideal way to watch that movie.
TLDR: My son watched T2 without knowing that Arnie was a good guy, and I think that is the best viewing experience for that movie.