Well, you made a good choice for your first tileset then. It's not been done before, so you can breathe a sign of relief here. Honestly, it looks great, but I can't decide whether it would look better in a grassland themed level or a desert themed level. I can see it working well in either. Nice job!
An oasis, now there's an idea, that would be a fitting theme for this tileset, though I"m sure there's also another theme this would be good for, apart from a cave I suppose, but I just can't think of it.