One being pretty good and the other being pretty lame.
Terminator 4 is a "reboot" of the Terminator franchise but unlike Star Trek, sucks at it. When hearing it was a reboot and then watching it, its almost as if "McG", the movies director, didn't understand what a reboot is. To be a reboot you have to star over. Yet throughout the movie "McG" can't decide if the movie is a sequel or a new beginning for the franchise.
It became clear that "McG" didn't want to ACTUALLY do the work of rebooting the franchise, so just made a sequel, but wanted to use the phrase reboot so he could do what he liked with the story, in places he wanted. Too bad nobody told him that this makes it confusing and a pain in the ass to sit through.
BUT as the title suggests, it wasn't all bad. The movie has a portion of it dedicated to Sam Worthington's character Marcus Wright. A man who, unbeknownst to him, is a robot now. His portion of the movie is good. His half boils down to a post apocalyptic road picture a'la Mad Max. The chases, the survival instinct, the fight with the robots on a day to day, non rebellion level, the not knowing the truth about himself. Very good stuff. When it cuts to the John Conner portions, you can't help but want the film to cut back because THAT'S where the real action is.
NOW to the second film. Which can be best described as a fanvid slapped together by the most close minded of fanboys. A fanboy who refuses to accept anything new when it comes to HIS beloved character.
Like for example Marcus Wright having a sizable piece of film, (the original script had John Conner in a smaller role) You can hear the cries of the fanboy "Excuse me, wheres john Conner? he needs more scenes in the movie sir."
Or like when its revealed that John Conner isn't the leader of the Rebellion, you can hear the fanboy scream, "Excuse me! John Conner is the leader, who are these old men in the submarine? No no I don't think so, they need to go, John's the leader."
So they die.
Or when John Conner "dies", the fanboy must have had a heart attack, "EXCUSE ME!!! JOHN CONNER CANT DIE! HES JOHN CONNER! KILL THE STUPID ROBOT MAN INSTEAD!"
So that's what happens. The robot man gives up his heart to save John Conner, and John Conner's wife, the VETERNARIEN, gives him a heart transplant. Why did we spoil the ending? Because it's lame and you would've felt worse had you had to see it after 2 hours.
The film has so far only made 208 million and being that it cost 200 million, we aren't likely to sit through Terminator 5: The John Conner Show.