It's the story of a young woman who learns to deal with the greatest resposibility of all, namely being the mother of the future and a chronoported soldier who learns that there's more to life than death and fighting. On top of this it's also the story of an unstoppable machine bent on assassination.
Terminator 2 is the story of a kid coming of age and reconciling his relationship with his mother and of an unstoppable machine protector who learns the value of human life and begins to experience real emotions. On top of this the characters are being chased by one of the best narrative excuses for a villainous special effect yet devised.
T3 is explosions, oneliners, bad CGI and contradictory and incoherent storytelling. It's in every way an emotionally and intellectually empty vessel and is representative of all that is bad about Hollywood's big summer blockbuster films.