Supernatural

Hi Guys, I was wondering if the skill Fell Swoop is any useful? If my lvl 55 WL is near a wall and mobs are all in front of me i have the feeling that i hit every mob. On the other hand when I AoE aggro mobs on an open field and i am surrounded by mobs i hardly hit more than 3. In both cases i am sure if it makes sense to learn the skill for the time being. Therefore any help is welcome.