It might be useful in certain situations but such situations are few and far between.
Pepole say that about a lot of weapons but I've yet to see one of those instances. Yeah sure it hits Nitro Man alot, Chill Spike is easier to use AND does more damage. Despite almost every weapon in MM10 being awful, I have to say Thunder Wool is the worst in the series Dethroning the Sakugarne as the worst weapon in Mega Man. Top Spin kills thing, Thunder Wool doesn't. Even if you wait the 7 years it takes for the lightning to come out, it only does 5 damage which can't even kill MM10's big eye eqivelant in less than 2 hits. Even the boss thats weak to it can be killed faster with other weapons!