It also helped that they made the good-guy terminator look like this:
Watching a doe eyed 16 year old looking girl be all bad ass and killer is as unexpected as it is entertaining. She's all confused and rattled one minute by our culture and then the next minute takes control of life and death situations and saves everyone's lives. After only the first episode I wanted to watch more just so I can see what she does next.
Sarah Connor is also as vulnerable as she is tough. I felt like the movie version of her was too hard, and her human side was almost dead as she devoted her life to saving her son and humanity. The tv version has a lot more hope in her, and the audience can't help but root for her not just so that she saves humanity, but so that she saves those hopes and dreams she had to give up and forget in order to devote her life to protecting her son.
I hope there is a second season. I hope it is available for rent.