I agree with the harness, you need to change it around so that it goes in an X-shape from the buckle. However I wouldn't try to connect the two as they are, because they don't actually cross. You also need to fix it and press it out so that you have a flat strap with the seamline hidden either at the back or the edge.
The other thing is the top stitching you've done is really visible. If you think the top stitching needs to be there, you should replace it with a thread that matches the colour of the fabric or just remove it altogether.
If you're comfortable doing it, I'd raise the hemline of the tunic. Hers ends just below her bum, whereas yours comes to nearly knee-length. You've done well getting the hem to sit higher at the front than it does at the back though!
Did you have much trouble keeping the sleeves up? You can either put a thin elastic in the top (inside the seam allowance), or look into getting an adhesive tape (toupee tape or even carpet tape from a hardware store) to keep them in place.
Overall you did really well, and it looks like you had fun!