yes, brilliant twist..and we'd feel "frustrated" bcoz of ben kingsley awesome portraying of the "mandarin"..but
at the end he just a decoy and we only get to know the real mandarin around the last 5min of the movie

Time and time, it's been said...

THE REAL mandarin is Aldrich Killiian (Guy Pearce).
Trevor Slattery (aka Ben Kingsley) is just a "decoy" to fool america the rest of the world. (IM3)

Must it be so lame & bloody obvious bad guys dress exactly LIKE as is?
Isn't it more sinister that the evil has brains instead just a mere caricature with a mask and a cape? 
For even in X men series, wolverine ditch the yellow/blue as in the comics but don black leather. He even make fun about it. (colours)
Think about it. Things aren't always that obvious.

For example, you can accept the painted "obvious" as how the present government tells you how safe is the country, of you can ask yourself, hey wait a minute... 
< sorry to use this example but since its election fever, perhaps such analogy is easier to understand

 
bro