TS pacing was just about perfect, the characters were spot on, there was lots of good action. It doesn't have any real flaws as far as I'm concerned.
Connor's wife is so thinly characterized, her pregnancy isn't even a plot point. Connor's followers, outside of Blair Williams (Moon Bloodgood), are ciphers, and their fanatical devotion to John Connor is barely explored. Speaking of John Connor, his screen time is so limited that he is allowed to do little more than bark orders we've already seen in the trailer--despite top billing, he is far from the lead of the film.
As far as pacing goes, the entire film feels rushed, unable to breathe between action set pieces. Not surprising, since 30 minutes were culled from the film at the studio's insistence, and I'm willing to bet twenty bucks it wasn't action the studio was gutting. When I first saw the film, I had only thought that the film had been edited to reduce the sex and violence to PG-13, but after viewing it, the exclusion of other scenes was painfully evident. But we can agree to disagree when it comes to the pacing.
Eflman's score is rather uninspired, and it ignores Brad Fiedel's theme entirely (outside of the occasional drum pattern).
Let's not even get into the uninspired plot points where Skynet captures Kyle Reese, but inexplicably avoids killing him, and later fails to kill Connor in the very heart of Skynet Central. Connor survives a heart transplant from Marcus and seems to make a full recovery.
That said, I'm not about to entirely trash the film. Most of the performances are fine, even though only a few characters are fully developed. Linda Connor's voice overs are a welcome addition. The cinematography and visual effects are top notch--even the liberal aping of other films (The Great Escape, Apocalypse Now, Blade Runner)is done with a soft touch. The action set pieces are all pretty clever. And Arnold's cameo in the end comes at exactly the right moment.
Decent? Sure. "Just about a masterpiece?" Not by a long shot.
Not that Star Trek wasn't rife full of flaws. But at least we understood Kirk and Spock's motivations, and how the other characters related to them.