I love this! This is my new favorite Dany picture (and it's about time, since my previous favorite is a few years old!). My only issue with it is that you made her hair blonde rather than silvery but eh, I'm sure you had a good reason--the piece is too good to begrudge that.
I shall definitely look through the rest of your ASOIAF stuff now. You have a great design sense, I think. I especially love the dragon-tipped scepter, it's just so--[i]so[/i] very Roman, which is fitting since Valyria is a Rome-analog. I love her outfit too, and I agree that the diadem/coronet is a lot better than the ridiculous crown they gave her in Qarth.
You wouldn't happen to have this in a larger size than 600x800, would you? I'd love to use this as a wallpaper if at all possible.