Image #1: nice big box with stuff inside. Break up the walls a bit. The repetitive nature of the texture only enhances the boxy feel.

Image #2: Great looking hall walls. Boring ceiling and floor. Put as much effort into them too.

Image #3: Boring ceiling and floor again.

Try hard to break these items up into chunks of irregular shapes and sizes.

Looks nice, especially the first shot. I like the trick to make the molten metal look hot. :smile:
Second shot looks not so impressive though, mainly that it's too long, could use something to break it up like some sort of machine. However, I think it's better to avoid too long hallways at all, for gameplay sake.

Could use some more height difference in floors and ceilings, those look quite boring in the end. You don't have to overdo it, just a few steps and platform height differences and such should do. Maybe spicing up some walls with a few pillars to break up the 90-degree look of it.

Damn, I bet you wont stick to this map too! Look I already saw you starting about 4 or more map threads in the time I've been here. My suggestion to you is to stick to one map and finish it!