i really like this, its pretty damn cool in my opinion. as usual, my concern is the colour. Very typical choices, no real variation. Im not saying to always change hues, but in general it looks nicer when you do. i need to stop editing peoples colours, but i find it enjoyable, if you take offense...just tell me and i will remove them. im just giving an example thats all. I just played with the colours, i didnt change anything about the piece other than the white outline.
whether or not you understand what im saying, i dont know. I hope these colours can show you that you can accomplish more variety with different colours. Widen your colour pallette and play around, no harm can come of it.