Mary worked with my son (a sophomore in high school) for nine weeks, and the change in my son's confidence with writing improved significantly.
Starting in first grade he developed a dislike for writing, which over the years turning into almost a phobia. He was so intimidated by the process, that he would rather fail than turn in an essay. As a result, he never really learned HOW to write, and his anxiety increased.
Mary worked with him, starting with the basics of how to map out and organize a persuasive essay. What took him hours before, he was able to accomplish in less than half an hour. It was very empowering, and helped him considerably with facing writing tasks.
One thing that I didn't expect with a writing tutor was Mary's incorporation of subtle life coaching. She had him examine his motivations and his goals. They even did personality testing. I think it was very eye-opening for him to have the chance to look at himself from a different vantage point.
Her approach is very supportive and validating. She knows what to ask to make you (both the student and the parent) feel important and interesting.
Finally, one of the things I appreciated most as a parent, was that she sent me an email after every session detailing what they had done and explaining her plans for the next session.
I can't recommend her highly enough.