Well to be honest, they sound better than they are. They can switch in on some super-effective moves, but they can't switch in on physical moves at all really. And from what I've seen, nobody uses Latios, the obviously cooler one outof the two, so as long as you prepare for Latias, you're good.
That said, my team kinda hates Latias, and it's still too strong. Nothing that specially bulky should have a special attack that comes out similarly to the other dragons in ubers.