As far as the plot goes, I have two problems.

Rating: 7/10 (8 March 2012)

Technically, this is a superb film that combines excellent sets with exceptional use of computer graphics and photography to create a better feeling than Terminator 1. However, as far as the plot goes, I have two problems.
Problem #1 is this conversation from the first movie between Kyle Reese and Dr. Silberman: Silberman: "Is that when you captured the lab and found...the time displacement equipment?" Reese: "That's right. The Terminator had already gone through. Connor sent me to intercept and they blew the place." Silberman: "How are you supposed to get back?" Reese: "I can't. Nobody goes home, nobody else goes through. It's just me and him." Therein lies the rub, as the Bard would say. How did the second Terminator get sent through by Skynet if its defense grid was smashed and the resistance had won? Now, to be fair, since Reese came from 2027 and the newly touted year in T2 is 2029, perhaps the resistance was premature in their boasting of victory and Skynet was able to rebuild the lab. But you have to admit, since we are talking about time travel, it does seem like a bit of an inconsistency.
Problem #2 is a bit more profound. At the end of T2, we witness the destruction of all of Dyson's work, the broken chip from the first Terminator, and the meltdown of both the T-1000 and the Protector. Therefore, if Skynet is never built, there is no Judgment Day, there is no time displacement device, Kyle Reese is never sent back from the future, and John Connor cannot exist. This would seem to preclude the making of a third film, but when logic and fantasy conflict, fantasy usually wins out.
There are a few other problems with T2, but they are not plot related. Edward Furlong, who was introduced in this film, does an excellent job of transitioning from budding juvenile delinquent to accepting his role as the destined leader of the resistance, but he is the only character that truly develops in the plot. Joe Morton and S. Epatha Merkerson do a fine job of portraying a family caught up in unbelievable circumstances, but overall this film relies heavily on the special effects and much less on the characters of the story. Somehow Cameron has lost the vision of Harlan Ellison and settled for the box office blitz as the purpose of the film. Rated R for violence and language, I would have to disagree and say PG-13. Collectible as the sequel to the original, by itself, not particularly.