I was a bit disappointed with the movie. I get that it's science FICTION and everything couldn't actually happen in real life, but come on. A heart transplant in the middle of the desert from an unmatched donor? A plot to lure John Connor into Skynet central, all the way into a cell, so Arnold could kill him? There were plenty of opportunities for Skynet to kill him along the way, if they were really manipulating Marcus.
Also, isn't the concept of "pockets" of resistance groups counter-intuitive to the whole idea that Skynet can easily destroy most humans? Any signal they were sending out should have been picked up by Skynet and responded to, not just when people play Guns N' Roses off an old school radio.
The actors were good, but even that couldn't have saved the movie. The pace was too slow in comparison to the fast action pace you may expect from the trailers. They also relied too much on the audience being really interested in the characters' powers, and gave the powers too much time in the movie. Overall, unless you have a burning desire to see Dakota Fanning brilliantly act drunk, pass on this movie.