I have been ordering these for my students based on previous reviews and inexpensive cost. I recently bought them for myself and I do not find them comfortable at all. If you are not used to good quality shoes, these are ok, but if you're used to top quality, these feel incredibly cheap. They hold up well for the students but as a teacher who wears them 6+ hours a day, 5 days a week, they won't last. I also do not care for the pre-sewn elastic as it is too tight for my foot.
We ordered these for our daughter and went by the operator's suggested shoe size, which is on the size chart. They fit perfect plus she has enjoyed wearing them in class. You will need to sew the elastic to the shoe after you have purchased them, which was fine with us as we could fit the elastic to her foot.