I have yet to encounter anyone using a poison that dealt enough damage for me to take notice of and I have cleared loads of Falmer camps. I have even taken out a lot before they knew I was there and the poisons they had at best did 20 damage.
Yeah posions are fairly weak in enemy hands, in the hands of a good assassin however, it can mean the difference between a 2 hit stealth kill and a 1 hit stealth kill

