1 priest 4 mage here as well. Full on frost spec. Wouldn't change it for anything. Kill most mobs before they even reach me. This includes bosses. Lvl 26 currently and going fast even with my play time or lack thereof. Frost bite is amazing and now im working on shatter which if i crit on multiple mages pretty much just destroys mobs hp.

all instances done so far for my level without issue. Give it a shot, you wont regret it.