Is mass thor attack good?
If your enemy scouted you: No.
If your enemy did not scout you and you’re aggressive: Yes.
I am not a Terran player, though, I am a Protoss who lost to such strategy.
Depends. In the lower leagues it will do the trick. The moment you hit plat or above people put early pressure and scout, so you will probably die before you get the thors out. Starcraft II is more then making one unit and try to win the game with it.
If you scout it build mass immortals they wreck thors, especially as the upgrades go higher.