It's nothing personal.
Why it is hard sci-fi
Soft on the time travel, hard on the enemy. The T-1000 is a liquid-metal mimetic polyalloy with a phase-change response to physical insult. The films rule for the unit is consistent. It cannot form complex machinery, only simple solid shapes and stabbing weapons. The kinetic damage model is reproducible across scenes. The premise is fictional but the rule is followed.
Science inside it
Mimetic polyalloys as a fictional state of matter with a defined behaviour set, neural-net learning chips as the in-universe explanation for adaptive AI, and the films one good engineering scene where Sarah Connor talks Dyson through what his Cyberdyne research will become. That scene is a real safety case argument.