It's very grassy for a desert! Deserts rarely transition directly into lush grassland, so it looks unnatural. Desert vegetation doesn't tend to form ground cover like grass does.
You've got a a set of tiles where the ground fades out to a solid colour, consider using those more and having more areas of just solid colour. It's a great way to add variety without adding any extra tiles, and there's no background less obtrusive than a solid colour. Having more solid areas would also fit better with your grass, which is mostly solid.
The cliff strata feel too clean and even, they resemble a stack of pancakes too me. Real rock strata are usually varied in thickness, have breaks in them, aren't perfectly horizontal, and don't have smooth edges. The bottoms of cliffs are usually not so clean either, there are usually rocks and sediment piled up at the bottom, having eroded from the cliff face.
Your edge tiles of all sorts feel very straight (perfectly vertical or horizontal), with only minor deviations for texture. This is fine if you want the tile grid to be easily visible in-game (useful for e.g. strategy games), but if that's not what you want, then consider having rougher edges. Don't be afraid to have the transitions go all the way to the edge of the tile. Only the edges need to remain consistent, you have total freedom within the interior of the tile.