the patterns are nice but its all grey grey grey.. I think you should get at least tiny bits of color going on through some slight dirt and grime.
Another suggestion of me would be to paint in some soft shadows in the diffuse to add more depth.
You could also crack out some parts here and there in the pattern to add some life. It seems to be a rather cavernous/porous material. You can either edit the normal map directly in photoshop for this or cut out in your highpoly.
Some wooden trims could work too. Wouldnt be that unusual with this kind of decoration.
Keep it on
