Your shading looks great. But I noticed a technical error with the gradients on large areas like the wall (which has nothing to do with your artistic skill). I suggest that in your color layer, you use a color blend or smudge tool (same thing, different name depending on your program) to help smooth them out. You can also do this with the highlight edges on your characters or objects like around Apple Bloom's body.



Oh, and I would keep your outlines as an absolute top layer because your highlight gradients are crossing over the black edges and bleeding off. A few programs don't have it but some can perform a color fill-select, where it detects certain shades of a color(s) and automatically isolates those areas. You can then play around with whatever you want within the selected area and the rest will be ignored. It's how NCMares is able to get complex shading all over the different surfaces on his ponies.



You have great cracks in the wall, but a few too many on the bottom with too much consistency.



The eyes are brilliant, my favorite part aside from the large crack and hole in the wall.