Yeah traps are great for the tough fights. They are especially nasty for fights on monsters like dragons that are not hostile when you first see them or a monster that will appear in a certain spot once you do something. Its insane the carnage you can do with some traps setup in advance. If you are fighting 1 target like a lich then you can often kill it before its sequencers like stoneskin etc even fire (well if that traps don't your first round of attacks before the sequencers fire should do the trick
I believ I have read several interviews with bioware people who seem to think they are one of the strongest things they put in thegame