How useful were Archer-class torpedoes?

How effective were the Archer class's torpedoes?

They were unreliable and slow, but still gave a small cruiser a potentially decisive deterrent against a larger ship.

Early torpedoes were unreliable, slow, and aimed largely by pointing the launching ship. A malfunction could even leave the cruiser in danger of running into its own weapon. The weapons were therefore awkward rather than useless. Their main value was deterrent: a much larger opponent still had to account for a small cruiser that might inflict fatal damage at close range.