in PvE absolutely its disgusting.
PvP... maybe, it his a little slower than sfb but hurts.
I much prefer SFB during pvp YYB is too slow and I see no difference in actually damage.
Although there is a 1 in 100000000000000000 chance you can purple/blue somebody.
Its another frustrating skill as in PVE its fine then suddenly a fight breaks out and im hiding in a corner trying to swap it back to SFB as I don't have enough keys.
You can get the odd 200 hit with a YYB in pvp (red poisoned) full sc however its few and far between and due to the time it takes to cast the enemy's usually screens away.