It seems like it's heading in the right direction but needs some tuning, especially on the palette.
The first problem is the grass tiles -they cover a very large area, and therefore can easily get repetitive, so you may want to create more versions of the grass tile , but also think about creating a variety of tiles that contain patches of differently colored grass,flower beds, dirt patches, rocks etc, just to break it up a bit.
As for the tile itself - it's extremely noisy, and feels uncomfortable to look at. I would follow Adam's advice and add another green - perhaps one between the two existing tones so you'd be able to smooth things out a bit.
The trees (especially their tops) have very high contrast and to me they feel metallic, like balls of tin foil. Perhaps you should tone down those highlights, and limit them to a smaller region on the tree. Search these forums for a great selection of tree sprites for reference.
The sprites are cute and easily distinguishable, but I think that that black lines used for detailing inside the sprite area are a bit too harsh and make them hard to read.