I'll just give a feedback about the general texturing of the level and the mood ;
Some places works very very well (http://i.imgur.com/KsEQLw4.jpg / http://i.imgur.com/lNAFIRB.jpg ) because of the simplicity of the materials and the good lighting setup.
I'm not joking since I know that you are using template texture but honestly, these works far better than some of the custom noisy texture you put... like the stone road ( http://i.imgur.com/ORiraBs.jpg )wich doesn't match with the rest (different color, fat join) or the ceiling ( http://i.imgur.com/2ZwpvZL.jpg ) wich is REALLY aggressive compared to the simplicity of the architecture. Some of the textures should be tweaked to match with the general look of the scene. In this room ( http://i.imgur.com/xyUprJ2.jpg) the planks on the floor are far too big and if it's supposed to mimic an old varnished floor ( Like this one : http://www.histoire-image.org/photo/zoom/noce-photographe-f.jpg ) so you should use other materials because this one looks like a generic Cgtexture rich wood.
(And for a french opera, the wall are very english styled.. lol )
In the big hall (where you have the flashy ceiling), the floors works far better from a far distance because it looks almost like a flat color wich should be perfect for readability. It 's certainly one of your best custom =)
This room ( http://i.imgur.com/xyUprJ2.jpg) is certainly representative of a bigger problem in this map : The artistical direction seams to be confused. On 3 Different screens, (
) I see 3 different maps and it gives the sensation that each rooms are worked very independently...If your map was unified on this point, you'll certainly gain like 1 month of development and lot of quality improvement.
For the next Step, I would suggest you to start with temporary quickly made textures before creating the final asset and having to retake them.