I like the style. Is that the mosaic filter you've used for the cracks?
I'm really not sure about the grid. It makes it look a bit like square flag stones, but that really jars with the cracks, that look like irregularly laid stones. You can't really have both The other thing that jars there is that the grid has a universal light glow, so the squares all have light edges, which just looks unnatural, especially with all the shadowing everywhere else.
Try putting in a more simple grid of just black lines on white and setting it to multiply, you can lay as much of a grid as you like by adjusting the transparency of the layer. Otherwise, very nice.