I've tried to come up with a reason why so many internet posters are virulently against this film. The best I can come up with is that they're comparing it to the earlier Terminator films starring Arnold Schwarznegger (who they loved) and were simply turned off by the lack of a central antagonist. In some ways, they're right--'Salvation' lacks that one fascinating villain so prominent in the early Terminator sagas. But to claim that this is the 'worst movie' they've ever seen, is way off the mark.
Salvation picks up the story of the fight between the Resistance and Skynet in the year 2018. 'Judgment Day' is long past but it'll be about ten more years before the final victory over Skynet is accomplished. Somehow in this new Terminator, the Resistance has a lot more hardware to work with (helicopters, rocket launchers, etc.) and the chain of command is delineated in much greater detail. Who knew that John Connor actually had a commanding officer?
Probably the best sequence director McG came up with in 'Salvation', is the Giant Terminator attacking the gas station. It's a non-stop, pulsating spectacle which also features a great car chase; watch the Giant Terminator belch out two 'motorcycle terminators' who attempt to chase down the neat little trio of Kyle Reese, the child mute, Star, and part-cyborg Marcus Wright. Wright escapes, but Reese and the kid get chucked into a dumpster, consisting of hostages taken by Skynet. Scenes of a post-apocalyptic holocaust are evoked as the prisoners are packed in like sardines in Skynet's holding pens.
Without the interesting part-man, part-machine character, Marcus Wright, 'Salvation' would be stuck with the interminably boring Christian Bale playing John Connor as a sole protagonist. Bale's performance is akin to Russell Crowe in 'Robin Hood'. Both display no wit or humor and play each part as hard-assed macho men. Boring, boring, boring! After the car chase, the Resistance somehow learns of some kind of electronic signal which might have the potential to destroy their mechanized enemy. Why it never occurs to anyone that this might be a trick on Skynet's part is one of the weaknesses in the Salvation plot. After all, an all-in-one, immediate solution to the Skynet juggernaut comes a little too easy to the commanders of the Resistance. No one seems to suggest that this might be a Trojan Horse type of situation.
We now arrive at Salvation's second main sequence: the capture of Marcus Wright. I can understand the Resistance being awfully paranoid and the fact that Wright himself is unable to recall the circumstances of his early life, but wasn't it obvious that Wright was markedly different than the Terminators who they were familiar with? The real terminators never had a 'conversation' with anyone in the Resistance and were programmed to kill; on the other hand, this Marcus character is being quite sociable with his captors. Even if you buy all the paranoia and the need for the soldiers in the Resistance to cut Wright no slack, certainly Wright's escape and manhunt could have been cut down in the editing room to a more manageable size. The silly chase seems just like filler to me.
Finally, Salvation ends with a whimper. With Connor's blessing, Marcus somehow gets past all of Skynet's security grids and ends up in the main console room. There, a computerized image of the female doctor who stitched him together before 'Judgement Day', reads him the riot act: Marcus actually had a computer chip in his brain that was placed there by Skynet. Marcus was used by Skynet in order to lure John Connor to Skynet's headquarters. Connor came to save his father, Kyle Reese, who Skynet had earlier snatched following the fight at the gas station. Bingo! Marcus simply doesn't want to be part of Skynet's game so he pulls out the computer chip from the back of his head. Whoopee doo! Contrast that with the machinations of the Star Trek Next Generation Crew when they have to figure out how to save Captain Picard from the Borg. Hey, it wasn't so easy to extricate Picard from the collective consciousness of the Borg until Data brilliantly figures out that the command to sleep will do the trick. Nothing like that here! Marcus simply tugs on the strap on the back of his head, and he's free from the diabolical Skynet!
Connor's liberation from the bowels of Skynet also wasn't much of a big deal. The Schwarznegger-like clone is a bit of a surprise, but all he ends up doing is tossing Connor around like a rag doll, instead of crushing him like an ant. And what happened to all the terminators inside headquarters? They've got one machine operational, and it's already 2018! As to Salvation's ending-'many purists were appalled that the noble Connor had to be saved by the second light half-Cyborg Marcus Wright via a heart transplant. Given Christian Bale's non-performance, any organ donations from outside the cold-hearted Thespian, can only improve John Connor next time around.
Salvation is certainly a flawed movie. As pointed out before, it lacks a central antagonist and relies on a series of fight scenes with an assortment of killing machines to entertain. It's a hit or miss affair with some battles with the machines more gripping than others. Although Salvation suffers from a lack of originality, the cinematography and editing are well done and the story moves along at a brisk enough pace to keep one's interest.
Review by Turfseer from the Internet Movie Database.