I'm going to go with the size of the letters.
Improvements to this would be: make the waistband black, shrink the letters some and don't rhinestone them but maybe a burst of rhinestones around them instead.
And I'm just over mystique fabric in general. Probably because we had a full mystique uniform three years ago. Now I don't like it at all. My next uniform will have zero shiny fabric.
ETA: see
@SarahS 's uniform? That's lettering done well. Nice contrast, great font, rhinestone highlights. Perfect.