If it's the maker's choices (style, pattern, colors, fabrics, technique, etc.) that are not to my liking, but the work is well done, I'd comment on the workmanship. If the workmanship is poor, but the choices show skill, I'd comment on one of those points. If all the makers choices plus her execution are poor in my opinion, I would say nothing at all. If asked directly, I would encourage her to keep practicing, still making no comment on the particular piece in question.