I think what he meant is the farther away from the figures the more nondetailed and abstract the piece; which isn't necessarily a bad thing it actually draws attention to the figures more; but it does give the feeling that not much time was spent on the bulk of the background.

Dunno for sure, I've had this feeling before about other pieces and found it hard to pinpoint.

It's about a large part of the bg, which looks like it was mostly roughed out and got no further.
The rocks on the left are ok: well-thought shapes, detailed at several scales down to the pixel (mostly the linear highlights).
By contrast, the corner just above doesn't work for me: the shapes are not really elegant, their level of detail is very uniform and low (uniform being worse than low).

I'm not saying everything should be detailed: the dark corner is good, the fumes are ok (although their curves might be improved upon a little I think).

Sorry to not be more specific ;)

Edit: hadn't looked at the painting yet. The upper left corner there is good because it hints at a mysterious watery distance. Of course how to pixel this is another matter entirely.
 

Thanks

but what part of this looks unfinished? I think this is pretty much what I wanted it to be.

Wow this is great, why does it look unfinished (because it is I guess)?

Also hi Tormi ;)

 Nice. I like the effect that the lack of dithering and the splotchy, minimal use of color create.

 amazing