Let's talk Terminator: Salvation.
The main problem with this movie is that pretty much the only plot twist (Marcus being a human-terminator hybrid) is revealed in the trailers. Half the movie is spent building up to the moment where his true nature is revealed, and it sort of falls flat given that most everyone already knows what he is from the outset.
Also, Marcus is by far the best character in the movie. John Connor is a disappointment for me, since he ends up being more of a side player to Marcus' plot arc. You'd think that a story about the war in the future would feature John front and center, but he just sort of wanders about, occasionally ranting about the future. I wanted to see his ascension to the savior of humanity, but it's never presented. The men just follow him, and we're never shown why they consider him such a great leader (despite the fact that he knew of Judgment Day before it happened, and knows a lot about Skynet). Christian Bale tries with what he's given, bless his soul, but it pretty much just amounts to him being angry for the whole movie.
I rather like Marcus, however, and I like the guy who plays him. He's got a good look about him, and manages to be convincing as both a murderer that is horrifying in his fury and a man who just looks kind of broken and sad and out of place. He's got a generic action girl love interest played by Moon Bloodgood who doesn't have a whole lot to do in the movie, but I don't give much of a shit, because it's Moon Bloodgood, one of my main Hollywood crushes.
Arnold's appearance is actually kind of cool, even if he's literally more machine than man (the CG effects to make him look younger and buffer are pretty obvious). But there's something not at all menacing about John Connor fighting a completely naked T-800, and brought to my mind that scene from Beowulf where you spend more time wondering how they're going to cover the naked dude's dick in the next shot.
I guess the ultimate issue with the movie is that it doesn't add anything to the Terminator storyline. It's thematically bland and derivative of the other movies. The storyline doesn't go anywhere new. We only glimpse one battle in the war, and at the end, humanity is still pretty much where it started. The only real advancement we get is the story of how adult John Connor got his facial scar.
I get that they're trying to make a new subset of the franchise with "machine wars" movies, but they've already made a dire misstep by killing off the best new character this series had thus far. But then again, it's Terminator. I wouldn't be that surprised to see time-traveling Marcus appear in another movie if he proves to be popular.
I think the most dire thought I had during the movie was during the grand finale in the T-800 plant. I had this strange feeling that I'd much rather be watching T2 on the big screen instead.