Yeah, so long as you're consistent with your art it should be fine.
Try thinking about making a choice if you want to have all foreground objects with dark outlines or just stuff you interact with.
The general shape is ok but the different shades of blue could be a bit more contrasting. It's almost impossible to distinguish colours so close together on a small sprite. The head does look a little flat though.
Still it's all pretty good, not exactly the best art ive ever seen but pretty good.