"What does he do?"
I love that question. I'd have to love the question to want
to play with a deck like this because that's all I ever hear, but I especially
love it when people point at Oros and ask it. "Not a lot," I'll
usually respond, "He can Sunlance everything for 2W when he deals combat damage
to a player."
"Seems pretty bad."
Actually, Oros is far and away the best commander for this
deck. I say that with full knowledge that Kaalia of the Vast and Tariel, Reckoner of Souls are, in fact, options for playing WBR. Oros is not the most
powerful commander - he's not even powerful at all. He doesn't have any special
abilities outside of Flying, you have to pay for his ability when he actually
connects (and lack of Trample hurts those odds), and when you pull the effect
off, you can't even hurt white creatures or kill things with toughness 4 or
more. Everyone who has said he's bad is pretty much spot on. Oros is a bad
creature, which is actually why I say he is the best commander for the deck - being a bad commander and a good creature are, in fact, two different things!