I'm not much of an artist, but it's seems decent overall. I especially like the characters.
My main criticism would be:
- The trees are clearly copy-and-pasted. There needs to be more variation.
- The rock/stone in the center seems to be too smooth. I feel as though it should be more rough.
- The windows on the house seem too small and lacking detail. But I guess it depends what you're aiming for.
- I can't seem to figure out what the house roof is made of. Wood? It needs to have more texture.
- It might be better to have separate tile sets for short grass and long grass. This would help make the grass more dense without copying that same grass sprite all over.
Hope it helps!