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Not bad, though it's a bit hard to give constructive criticism with those photo's.
Having said that, minus-t at the centre of the GD universe has produced a guide to miniature photographing which I think you should look at.
But all in all it seems nice - thanks for sharing.
Diabolus fecit, ut id facerem!
All in all, it's very decent with the exception of the gold. GW paints will not do gold justice unless you mix mithril silver and a buttload of others, or if you do a non metallic gold, which is very difficult. I'd suggest reading a few articles on non metallic gold and practicing. If not, buy some burnished gold. From the looks of it, you used shining gold which is ok but has too much of an orange tint. Burnished gold has a nice yellow polished look. For a final highlight, you could mix burnished gold and mithril silver. It seems wierd at first but it actually looks quite nice, as the newer GW ultramarines have proven.
The skin looked nice but I think Abaddon should be a bit paler and should not have such a big dark/light contrast. Maybe make Dwarf flesh the darkest color or something to that extent.
The bones are nice but I feel that they could have had one or two more layers of highlight, by adding a bit of skull white to the bleached bone. It might have been a good idea to make the tyranid skull and the human skullers different shades, as well.
Oh and the base is excellent, well done!