Just wanted to add my two "sense" (mispelled on purpose).
While the movie may be just as good with Mandarin as the villian, I would have picked another villian at this point.
The movie will have to spend enough time with its origin - Mandarin requires his own amount of time to develop. Mark my words, splitting the story to explain who/what/how he came along will detract from Iron Man's own storyline.
On another issue, Iron Man really needed, as a first villian, someone he can go all out with....pull out all the big guns, etc.
Just to let you know - this is a standard I believe in - when you make the 1st movie for a superhero, you don't have him face his greatest villian...unless that's the only villian he has.
Superman vs. Lex
Batman vs. Joker
Captain America vs. Red Skull
Daredevil vs. Kingpin
...and so on.
In my opinion, the first movie, should quickly establish an origin and let the hero bash it out with his or her new powers. But I'll restate this: the focus should be heavily on the hero. I thought "Batman Returns" did this nicely. Little, but enough of Scarecrow, and more of the evolution of Batman.
The second movie, however, or third, or fourth, etc., is entirely available for the hero's main villian. Now that you know the hero, spend the story on this great villian, have them clash, and see the drama.
Anyhow, I won't dog a movie I haven't seen. And, of course I will see it. However, I wish the villian could have been Ultimo or Crimson Dynamo. Metal to Metal, no holds barred, lashing out action.