Your animations look nice. I think you could benefit from playing around with color contrast. You should zoom out all the way to 100%, if you can't differentiate shades relatively easily then those colors aren't serving a big enough purpose and should be made darker or lighter. From far away your C Shepard looks like he only has 2 color blocks used for his body, a navy blue and a darker navy/black area. But you DO have shading there, you just need to up the contrast and your shapes & details will be more apparent. Your skin tone isn't really working with that lightest shade, it needs to be less yellow and more pink like the other shades, and lighten it up a notch.

Being a pixel noob, I will stick with abstract advice and lean away from actual in depth pixel art techniques..

I think:

1.  You should post any other background/sprite examples you may have so we can see how it coalesces and fits in.  Imagine if in the beginning stages of Minecraft, a pixel artist sent in the pickaxe sprite for editing here, and some forumgoer made it all badass, but guess what, now it doesn't fit in with the style of the rest of the project.
2.  You could tell us how much time you have for this project (college, cool) and how long it took you to make this so we can make an accurate judgement of how much work you may put into your project.  1,000 hours is a lot more time for shading and dithering than 50 hours.  Also are you going for a decked out game along the lines of Final Fantasy, or following a concept as simple as Frogger?  That weighs in big time.



I like it.  You obviously worked at it to make it a smooth walk transition.