It's basically all you need it for from emily's blog

You can use Arcane Missiles, which consume this and bar WoTLK Gold proc. This is basically what makes the arcane specification the one it is. 

Also, we have two new abilities that boost effectiveness of our spells and also it's Critical Strike damage bonus of all our spells. Then we have Arcane Barrage, so you could imagine Arcane Barrage as a fire blast, however in Arcane Tree, it's a quick casting. 

It's got traveled time however, unlike Fire Blast, which has no travel time. On only a couple of minutes. The target was a time of three seconds, so it's just a, powerful move spell. It's basically WoTLK Classic Gold all you need it for. It's not a good idea to use this to dispose of your stacks.