I see it like this, T2 was mainly to commercialize the Terminator. Cameron had the money now, he's a sucker for special effects and big movies.
T3 tried to take the Terminator back to his roots, more violence, overall darker movie, it makes T2 look like a family movie or almost comedic. The Terminator learning not to kill people and how to make jokes, taught to him by a 11 year old kid, GREAT idea.
T2 was all about the special effects, the "story" sucked big time.
SPOILER WARNING
What i liked about T3 was the plot twist at the end that they couldn't stop judgement day but were "tricked" by the Terminator into saving themselves, thus making the transition to the time after Judgement Day.