So far I like the way the maps look textures are crisp and clean.
A few suggestions to make things better, and easier to use.
A brush feature for assets, it is tedious to place 600 trees or floor tiles to make a room or forest that with a brush could take moments.
The ability to set a size numerical by grid when you place a tile. Say you want a 35 foot by 30 foot room. A place to type in Height: 7 Width:6 that would then place a texture in that space.
A polygon shape function with a texture fill so you could create odd shaped rooms with just a drag of the mouse.
The ability to sort added assets in the vault. Like a “new folder” system where you can create and name a folder to help you keep thousands of images straight while map making.