I've spent this weekend updating the lighting and effects, I've added Normal Mapping to all the walls and it's looking good now. It took me a while to make it look right, either it was too dark or too bright but I think it's just about there now. These effects can be turned on and off by the player, in case they are playing on a slow laptop or something.
I've also noticed the dungeon is a bit 'static', there's not much movement. So I'm going to add some animated objects, things like torches, swinging chains, tapestries blowing in the wind etc. In the video you can see the 'torch' effect.
It's a flat polygon, which is rotated to the player, textured with a flame texture.