Photoshop has a strighting tool , this would be the perfect picture to use it on . If it was stright I would give it a 10 but I am knocking it down to a 9... I really the simplicity of the photograph.
Watch your camera positioning, and it will help make the wooden slats square up. (Tilting forward/backward/side-to-side.) :) I like the sparse blades of grass growing between the slates.