The pattern is simple but looks nice and blends with her eyes and the rest of the costume well. The super long high-waist skirt is super cute and goes surprisingly well with the dark boots. The blue cloth around her shoulders wasn't necessary, but it adds a bit of depth to it and helps break up the pattern around her chest, merge the skirt and dress together, and flows with the direction of the collars beneath. The hair ornament is a nice piece of visual flare that falls into the usual spot of her left-side head ornament (Ui-mama must favor drawing things to the left side of her head), and the big red bow on the back of her head is SUPER CUTE and I always love seeing it behind her when she's smiling and bouncing around.
I love all of Subaru's costumes and can give a lot of praise for them, between personal taste for their style and my tomboy favoritism, but this one just feels especially cute to look at and Ui-mama did a great job designing it. She's done a great job with all of Subaru's costumes, really, and it makes me enjoy and appreciate Subaru more.