Not bad, not bad at all...
I think you need just a few more things to clutter the corners up... look at indoor for things (i dunno why, but i think the pots would be a great clutter-er for this dungeon). Also, i suggest you consider using the two floor masks that look like a pile of really dark dirt--not the green-ish dirt you used already, but the black stuff. There are two of them. Use the large one about as much as you have used the green dirt already, and use the small one a bit more

(it doesn't take up as much space on each tile, so it blends in much better). Try to avoid putting them in the middle of the scene; put them more to the edges so that they aren't noticed so much.
Also, good job with the ruin debris

. As with the floor masks, you might consider putting more in the corners (i'd do it only if i had more than one version of them. I can't recall if we do...).
Cheers,
Unislash