Thank you for your comments so far, I've polished/tweaked/edited over the last couple days and I think I can call it done for now until I inevitably revisit the piece at some point!

I love the clean style and the colours. My least favourite part is the cracks. It just looks a bit too simple and unrefined compared to the rest of your piece. Just a minor niggle. 

Fantastic! 

Thanks for the feedback, I am pretty new to pixelling but from an illustration background; this is probably my fourth or fifth attempt at pixelling and my second attempt at AA and I think it shows the lack of confidence I have with the technique, I agree on the blurriness issue theres an area on the left shoulder where I can see this quite clearly. I struggle to know when to AA and when not to and I think also in the attempt to be too scientific and using AA on pixels with two surrounding colours I have unwittingly expanded the palette beyond intention. I will tighten the piece up in the coming days and see if I can polish it. 16 colours sounds good, I'll try and work to that restriction :)

EDIT: should have fixed the colours now have uploaded the reiteration

I think you might've overdone the AA a bit, the piece looks a bit blurry.
Checking the colours in it, I wonder how much of that is intentional - you have a number of redundant colours in the AA. This piece uses 40 colours but looks like it should have under 16.