I went in to this movie thinking that it was going to suck horribly, but it really wasn't that bad. Salvation had great action and some of the best CG I've seen! However the story was lacking and failed to get you to care about the characters (with the exception of Marcus Wright). I think he is the one that really saved this story if he wasn't in it the movie would sucked. The only thing was I couldn't tell if this movie was about John Connor or Marcus.
Also the fight scene at the end was awesome, and the ending was a surprise.