It's good for hitting that weak point when it's not facing you. I noticed that where with High Yield I might waste the effect on a well shielded side as they turn away from me, torpedo spread seems to hit the target all over, so more of the damage gets through the shields into the hull. Mileage may vary.
Also, not good to use this if you're an escort in the middle of a fleet battle as the first one to fire. It gets you a lot of agro. It's sad though that they put both skills on a cooldown. in CB I could charge high yield and then torpedo spread and fire three high yield torpedoes.