This has a good deal of control! I skipped out on commenting on your previous piece (though it suffered the same resolution issues the first one ended with) but this has none of that. Despite being very small, it's nice and shows good control over the pixels.
There's not too much to critique really. The red and white stripes are technically banding but don't read like it thanks to their extreme contrast and banding is inevitable the smaller you get, the visor could be a bit larger or more frontal to make it easier to read, and two of your colors fade away into the background at 1x - the middle grey (looks black) and darker orange (looks like the brighter orange) aren't really helping much.
I suppose a very small note is that the "7" in the N7 might look more natural if the slope was thicker and the bar across the top was a bit thinner.
I'm really scrounging the bottom there for things to mention. You're getting better, and fast.
Looks good, I don't really have anything else to add :)
It seems to be working fine in this piece, but as a note for future pieces: single pixel dots like you have with the belt don't read super-well unless they're highly-contrasting. Because this piece is so small and is probably viewed at 2x it's not a problem here, but figured you should know that.
Oh, and just so you know, Pixeljoint has a reply function for posting - if you click the little reply button in the bottom-right of a person's post, they'll get a notification that someone's replied. I've just been coming back regularly to see if you've posted again, but replying makes most users' life easier.
Seeya next piece, keep up the improvement!