Wow, good debate! I can't say I entirely agree with the statement that Roy isn't well devoloped, though. True, the glimpses that you get into his personal motivations are brief, but I think that is just part of who Mustang is. He definitely presents a mask to most of the world, and I think this what makes him somewhat opaque to the audience and other characters alike. However we do see other sides of him. Part of this is exemplified by his deep friendship with Hughes. You also start to see deeper parts to him in episode 13 with the flashbacks to the boy he killed in Ishbal and in episode 15 (I think) when you find out
Spoiler wrote:he killed Winry's parents on orders from Basque Grand and nearly killed himself.
Because of things like that he doesn't seem to let many people get close. Also you continually see throughout the series what a canny politician he is- he seems to be pulling all kinds of strings in his bid for power. So just because Mustang's more complex emotions and motivations aren't explicitely stated doesn't mean they aren't there. And the same can be said of Ed and Al. I do agree that some of the other peripherial characters like Havoc and Hawkeye aren't terribly well developed, though.