Well let me say I like where you're going with this . I like the color combination that you're using. The color palette is a bit washed, but I can sense a sort of "knight blade" kind of feel with this one (Where the colors fade to black or gray) It can work granted you work on your directional lighting
Another thing I noticed right off the bat is that the object are a bit out of perspective. Remember, you're going for a sort of distorted overhead view , where you can see the complete top sides of objects and the sides almost as though they aren't distorted. I edited a couple of the object so you can see what I'm talking about
http://img467.imageshack.us/img467/364/ ... hedeu7.png[/IMG]
Also I noticed that the floor tile is colored using a different method .I suggest staying away from that if you're making a limited color tileset. It's going to stick out like a sore thumb and it takes away from the harmony of the tileset.
Overall I say keep it up man . I like where this is going and I think it could be a great tileset. I'll keep an eye on your progress =)