I wouldn't have minded the ending either way -- the clothes being real, or the clothes not being real -- but I just wanted to KNOW.
I thought not knowing was a good way to go, myself.
I thought it sort of was the point, yes? The idea that the prince, who I think I liked more than I should have, essentially is destroying himself believing everyone is as wrapped up in secrets and lies as he is. You never really CAN know, in a world like that.
I guessed the twist but was kept on edge anyway, because the story made me unsure enough as to whether it was going in that direction, and the payoff was still excellent. I liked the subtle racism and sexism on the prince's part - unsettling until you realize it purely IS through his eyes, as are most of the -isms we carry, and it damages him as anything else in the failed plot.
Not sure if I like the boy from the original tale putting in an appearance. It broke the flow of the scene, somewhat, like it was there because it had to be, but it also lent the interpretation that maybe the crown prince caught on from that, wasn't an idiot, and beat his brother at his own game.