in single target its good although for mythic+ to get some more potential you will need to have as many FS`s as possible what that mean you will need to use FS > ice strike > fs > PW> fs > lb with target cycling and all shit around it, for me its clunkines in pure form tbh even worse than channeling for ~3 sec as that don`t require nothing beside standing still for duration and dmg is actually good for single target and aoe alike :P
You can pair it with fire nova tho but i`m pretty sure its not worth it in current form and with rather strong alternatives that's don't require so much effort ;P
If it would spreed FS to 2-3 extra targets instead applying it to one that would be different story
I'm going venthyr personally although for everyone their best i assume ;P