The comparison to twin strike was just to say that, as written, chaos bolt is not the most powerful at-will - it is not broken if you just play it by the book.
Sure, it is a good power. Still, the probability of killing a room full of minions is so small that I would not stake anything on it. With a 50% chance of hitting and 50% chance of rolling evens, you are already lucky to hit 3 targets with it (about 3% chance of that).
Also, you deal full damage only to the first target, the rest take 1d6+dex+enchantment.