The Reason, i'd say it got voted down would be the Gun. Specifically the bit just above the hand next to te head, basically front and centre and almost the first thing a browser sees.
That small area has a lazy highlight. Its a little too thick, and it not blended. The Butt, below it is has the grey highlight blended in, the smaller tubes above it are gven thinner lines. That small section stands out like a sore thumb as a rushed finish.
I should know check out the gun on my Khorne Jugger. It was a big mistake by me. I think I see it with you too.
Apart from that tiny piece I really like this. The highlights are VERY smooth, the glass scope is First Class, the fore arm holding it is great, as are both hands.
You deserve a 7.something in my book.
In response to your shout, I actually think this is way under rated at a 5.9. The only two reasons I see for the low score may be that the mini itself isn't terribly exciting and also the high lights could be a bit brighter. Other than that I like your style, very clean and realistic.