To us, this is one of the best of the stories by far. We know that we are completely in disagreement with most everyone else, who consider the second to be the best, or the first. We don't care. This John is so much superior to the snarky, smirking John of Judgment Day. The more mature attitude from John is refreshing. We continually think of John's speech to Kate.
Just imagine if you knew you were gonna do something important with your life. Something amazing. Maybe the most important thing anyone has ever done. But there's a catch. Something terrible has to happen. You couldn't live with yourself if you didn't try to stop it, but ...
But? But if you do stop it, then you won't be the great John Connor, you won't do something amazing. It's a dilemma, and this conflict is well portrayed.
Kate is a wonderful character. John says "you remind me of my mother" and there are similarities. Not with the Sarah of the second movie, but with the Sarah of the first movie. She is strong and independent, up until she slips her hand in John's at the end of the movie which, while slightly out of character, worked for that scene. The interaction between John and Kate is wonderful.
Again, as with the second movie, a large part of this movie is special effects. My understanding is that the scene in the cemetary when Scott is walking and turns into the Terminatrix, that scene alone took 6 months to create. It's not worth it, really.