It's a very good movie. I fully intend to rent it when it comes out on DVD, so I can catch whatever I might have missed the first time around. In this movie, John Connor(played by Christian Bale: swoon!) is a soldier. He's not leader of the resistance, yet. The machines have taken over, and are in the process of eradicating all humans. The Terminators still look like machines, not like people. John hasn't yet met his father, Kyle Reese, who is still a teenager at this point. But the machines know who Kyle is and why he's important, so they're trying to get to him before John does. John is assisted in his quest by a human/machine hybrid, which the machines created for infiltration.
The original Terminator makes an appearance, but considering how he looks and the fact that he doesn't speak a word, I'm pretty sure he was computer generated. However, his famous line, "I'll be back" is heard, just not from him. It's a great story of bravery, trust, redemption, and insanity. And there are lots of awesome guns. All in all, a terrific movie. Go see it.