While I don't want it to be the end-all talent for mages, I think there as some factors that should improved. I think the fact that it doesn't break roots or snares make it feel rather weak in situations where you are being trained by melee. If the fear is that mages will have access to too many ways of breaking movement impairing effects, then I think it would be suitable to at least increase the duration of the speed boost to 3-5 seconds, so we can get away from the melee before being obliterated.
Another idea I had, was for Blazing speed to have a secondary effect, where if you are brought below 35% HP the cooldown on the ability would be instantly finished. I think it would make the ability cooler, without driving it into OP territory. It would also be a a more interesting alternative to the somewhat, set it and forget it, nature of Ice Barrier.