I have worked with Mylène for years, and in different companies. I have seen her work in very different environments, for very different projects and with a wide variety of stakeholders—product leads, engineers, other designers etc...
The one constant has always been the excellence of Mylène output. She is, without a doubt, one of the most skilled product designer one could hire. Her analysis are top-notch. Her technical know-how is excellent. Her speed is borderline scary.
These qualities could be offset by lacking soft skills—but there too Mylène has always proven excellent. She handles feedback perfectly, and strives on it. She easily understands technical constraints and calmly, methodically finds the most positive consensus. I have never seen a designer drop an idea they had worked on with such passion so gracefully as her: if "it" doesn't work, Mylène will find something else without looking back.