The BBC review starts with this:
Not only is it a landmark in the advancement of special effects, but it is also one of the most effective science fiction films of recent decades.
The New York Times says,
ARNOLD SCHWARZENEGGER is about as well suited to movie acting as he would be to ballet, but his presence in ''The Terminator'' is not a deterrent. This is a monster movie, and the monster's role fits Mr. Schwarzenegger just fine.
EW calls the movie
a marvel of low-budget innovation, a pinnacle of romantic sci-fi, and the best movie that Arnold Schwarzenegger has ever made.
The Dancing Image has a review.