Irene was a very cool character in canon, but she was never a classy character. She was a high class prostitute, who was tricked into giving away her biggest asset by the guy she had been warned about and she should have been prepared for. Only her quick thinking saved her and let her get away, beating Holmes to the picture.

I actually think they did a pretty good translation of Irene's character, I just wish they had let her win just like in the books, because that part was a big disappointment for me.