Good looking movie but didn't work for me.(spoilers)

Rating: 4/10 (12 February 2014)

This is more of a review of why I don't think it worked.
Back in 2005 I was living in New York City, a friend of mine who knew some people in the business discovered a rumor about the ending of the next Terminator movie.
The rumor was John Connor dies and his face is surgically placed on a reprogrammed terminator. They do this so the people don't lose hope in their savior. The terminator(Connor) learns from the tapes his mother left him. He leads the human rebellion to victory.
I believe this to be true. After seeing Salvation I felt odd when the movie ended. I realized I didn't feel connected to Connor at all. We had all watched this character grow through the other movies though I felt no connection to him in this film. I did feel more of a connection with Marcus though.
Then I thought to myself, they focused more on Marcus than Connor in this film. Why? Why would they do this? He's a machine and dies in the end? Connor's supposed to be the hero, the one we take the ride with and it did not feel that way.
I feel this is proof the original script had Connor dying in the end and the terminator we had formed a connection with would take his place. It seems to me the studio did not like that ending and made the switch late in the game and failed to realize the entire movie was based on and leading up to this event and did not work without it.
They couldn't go back and rewrite the entire thing so they just made a few changes, gave us this hacked together movie and took our money.
My question to the writers/Director is, how was Marcus so advanced when he was built in the past? Even if he was built in the time the movie takes place, how is he so advanced when Skynet is just rolling out the T-800? It doesn't make sense. The only thing I could think of is......Marcus was sent back from an even further future. In the end, this movie is a mess.