Texture is used here to differentiate information and sets the tone of the piece. Color differentiates at first glance but the texture gives depth to the image.
Texture is used, along with color, to establish space by separating the wall from the floor. I like it because it is subtle but achieves the right affect.
This image reminds me of a fragmented landscape with all the layers of varying shades of blue. It comes of softer because of the color palette but also the paper grain texture.
Picture taken from http://veredgf.fredfarm.com/textura/index.html