I started to watch this once before, but didn't get very far. At the beginning, it feels very melancholy. But, now I am so glad I persevered and watched the entire masterpiece that this show really is. All the performances are spot on and perfect, but IU gave a stand out, lifetime achievement kind of performance. She developed the character, and was true to her the entire way through. Now it would be impossible to imagine a different actress in that roll. She and Lee Sun Gyun worked together seamlessly, and the results were phenomenal. My Mister is not to be missed!