When it came out back in 1984, “The Terminator” was a wild ride full of action and adventure with killer science fiction hook.. It was so good that few people noticed that the sequel, subtitled “Judgment Day” was ostensibly the same movie. By “Terminator 3” people were beginning to catch on, so, for the fourth entry in the series, the producers moved the action out of modern-day Los Angeles and into the post-apocalyptic world that was only scene for brief seconds in the earlier films.

While the first three entries had one story between them, “Terminator Salvation” can’t even boast that much. It’s sort of about John Connor trying to save his time-warped father’s life. It’s sort of about a multiple murderer/cyborg trying to find his humanity. It sort of wants to be about human nature and the battle between free will and predestination. But really, it’s just about the cool-looking robots and the big explosions.

And on one level, I’m all for that. I mean, the terminator is a friggin’ cool monster. I could watch like a dozen post-apocalyptic war movies about that thing. Or at least I thought I could…

I really wanted to like this movie. The concept seemed so fertile, the actors seemed like such interesting choices. I even sort of liked McG’s “Charlie’s Angels” flicks. But there is just no meat to this movie. It’s boring and confusing as a stand-alone narrative, and utterly useless as an expansion of the Terminator mythology.

Christian Bale’s John Connor is a totally blank slate. He’s so visibly bored that he seems like he should be in a zombie film. I can’t really blame him for taking a paycheck movie after years of physically draining roles like “The Machinist,” I just wish he were slummed in a more interesting picture. Here he has no arc, no personal investment and no real participation in the plot.

Come to think of it, no one has an arc in this movie. Helen Bonham Carter, Sam Worthington, Bryce Dallas Howard and Anton Yelchin are all saddled with incredibly boring characters. The movie does pick up a bit when rapper/actor Common is on screen. Even though he is seemingly reprising his role as “black weapons expert who stands around being black and not talking” from “Wanted,” he just oozes charisma.

Normally I wouldn’t be so harsh on a movie that exists for the sake of spectacle, but here, I couldn’t help but examine the logic flaws, character shortcomings, gaping plot holes and persistent use of deus ex machina.

McG, aided by cinematographer Michael Fitzgerald and director of photography Shane Hurlbut (the latter of whom was the subject of Bale’s infamous profanity-laced tirade during shooting) can’t seem to figure out how to shoot an action scene. I’m not even talking about the trend of super-fast cuts between whirling handheld cameras that has become so popular in recent years, I’m talking shots that are simply missing. On several occasions I found myself disoriented because the characters seemed to magic their way around a location, jumping from one place to another without any connection between shots.

And what’s more, the movie is simply ugly to look at. The de-saturated color palette was probably meant to make the movie look gritty, but instead it leaves the images looking bland. Every location looks the same. Not even the burnt-out husk of Los Angeles gets a rise.

But the real problems begin with the script. There is just no reason for this movie to exist. It has all the impact of an episode of “Power Rangers.” Nothing is at stake, and at the end of the day, nothing is gained or lost.

At one point the movie ended with John Connor’s death and replacement by a cyborg. This might have made for a cool movie, but for whatever reason the producers got cold feet and went back for re-shoots, changing the ending into a weaksauce variant on this concept, which is all well and good — except for the fact that no one ever went back and fixed the first two acts so that they would match the new ending. So, as with the recent, and infinitely more entertaining, “Star Trek,” we are left with a movie that seems at war with itself, dead set on not paying off a single setup.

“Terminator Salvation” shouldn’t be a movie. It’s barely passable as Internet fan-fiction. Stay home and study for finals, you’ll have more fun that way.