The parchment background is very nice. Good job with the shading, though I would add a subtle shading on the inside of the walls as well.

But, to be brutally honest, I dislike the grid, a lot! It is to prominent, to bright, to distracting and the color doesn't fit.
My bias is I don't like grids, period. So, it's me, it's not you.
My advice is this: If you play an RPG that is reliant on grids then add the grid before you print the map but keep it as subtle as you can. Your players deserve to see how great your map is.
BUT, When you are creating a map for a contest, for your gallery, or to share with others, don't use a grid. Your map will look better, and get more positive responses. There will be some who will ask for it with the grid for their games so have a gridded version available for them. Then everyone is happy.

And please remember, this is just my advice, from my point of view. This is your map, so feel free to follow it or ignore it as you choose. Either way, the map is coming along great.