The overall composition is fine, but the photo lacks impact due to the lighting and lack of sharpness in the nose. The eyes in particular should be the sharpest point in this photo, but I can’t tell because they are so dark. The harsh shadow above and to the left of the head makes me think this was a flash photo. Regardless of the lighting, it comes from the lower right, this leaves the upper left part of the head too dark. The lighter parts of the turtle draw your eye away from the turtle’s head and eyes.