It looks fantastic, the converting is great, the fire is really cool. Only thing would be possibly highlighting the blue armor, and maybe the fire some more, with a lighter color. Other then that, its great.
You have got to love thw old GW chaos models. I like the fact that you have stuck with 4 main colours for the piece, the one thing I would like to see though, is a little bit more highlighting/shading on the blue and headcrest. :D