looking good wilson. Going to give crit since you asked for it mate.Are you saving your darks for accents or are you about done tonally?I think you could play up the overall tonal pattern arrangement a bit more, it seems to have gotten a little watered down during the painting process. Maybe try and reiterate the original design of the tonal arrangement: seperate your tones out in to distinct areas. I think accents could also help pop some bits here and there although you are obviously going for a very diffuse feel i think a few on the siren herself where heavy occlusion is happening could help add some snap. Looking ace all round mate, lookingh forward to seeing how it comes out mate.
thanks jake - i'm trying to be as understated with the values on this as i can be, and stay away from popping out the speculars/highlights and digging in the shadows too much. Like you said, trying to get a very diffuse misty light, but i'll be playing around with things a bit still. For me its much easier to add contrast than take it away so we'll see where it ends up!