Here's my opinion on Glacial:
Annoying? Yes. OP? Probably not...
Every time I see or play glacial, the result is generally the same: Gets to #4 or so, and then just gets obliterated by teams that have damage before it can lock down a win.
Units are generally all expensive, so it's hard to get to (6) (2 Coin, 2 Coin, 3 Coin, 3 Coin, 4 Coin, 5 Coin) or get 3 stars.
Items don't really work the BEST with it (although Voli/Ashe do have strengths with them, Voli doesn't always last long enough, and Ashe doesn't have strong aoe apply of on hit debuffs)
Gunslingers/Nobles/Imperials/Mages all seem to beat Glacial atm once they are developed.
P.S. Glacial WAS nerfed; It used to be (6) 60%. Now it's 45%.