Stop loss, good or bad?

It all depends what you are trading and your trading style but I would say a stop loss is vital for most people to avoid totally blowing your account.
 
I don’t see any disadvantage of SL unless setting is into a wrong place! SL is the best tool to protect traders trading capital.
 
For sure, SL should be in a right place, or it would cause additional losses. The level to place SL is as important, as initial entry level, but only few traders understand it.