As far as pixel art goes this is pretty awesome. I think that building a sense of depth through pixel art has to be pretty hard and you did it very well. I kinda wish there was more going on but this is fine as is. I think some color variation would be awesome. Right now it's very mono chromatic. I think more value in the background would be nice instead of just 2 flat colors. I really like that you used a full range of values. Another thing I also think some more detail on the character wouldn't hurt.