The update looks much better than what you had before, and I have to say you're progressing very well.
The first thing that pops into my head when I look at this, is that while it's not pillow shaded, you didn't really flesh out your forms at all, so it looks more like some sheets of colored paper than a black ops dude. When you're making a sprite you need to dive into depth to really make your sprite look like something that can kill the bad guys.
Note; I edited over Corsair's edit 'cause I was lazy and liked his color choices.
What I did in my edit was first fix up his posture and proportions; pulled his legs in slightly, and moved his arm one pixel in, then made both his arms a few pixels longer.
Next, I foreshortened his left (not our left) arm because I see him as facing slightly away from the viewer.
I then took out the highlights on his left leg and arm to make them appear further away.
After all that I went in and started to block in what I thought the armor should look like when he's inside, then refined it when I got most of the kinks out. You don't need too much anatomy knowledge to pull this off, just enough to know the basic proportions of a human, and the size and shape of different muscle groups. Of course, I'm not very good at anatomy at all, and see plenty of mistakes in my edit, so maybe someone with more experience should help you with this.
I removed his banana feet (in yours it looks like his toes curve up at the ends, like a banana).
Then I tried to make the visor look more like a visor and less like eyes. Usually a shiny visor at this size should only have one bright highlight, and some buffer shades around it except where the glass curves and goes under the helmet.
Tweaked the colors, and was done!
If you notice anything in my edit that I didn't mention, or didn't explain well enough please ask me about it; I'll try my best to answer what it is.
