You can tell the neck is wierd just by how the collar of the shirt needs to stretch. I suggest you to observe the distance between the eyes for Sakura. Big eyes can be great for a stylized look, just be careful.
The colors and the background look good! But the petals or the whatever effect looks kinda cheap. You could use some Sakura references to nail minor detailslike the nose. Even with mistakes I can tell you made great efforts in this piece. So keep it up! :)