Hi all let me know what you think. This was an attempt at creating a photorealistic walkthrough with Vray render quality. Critical feedback always welcome. 
From lack of a better world, amazing. I love the scene, materials and lighting so far the best example of UE4 architectural visualization in my opinion.
What?!!?!?
Lighting in the first picture looks a bit weird, but man this is some quality stuff!
I would love to see it under different light conditions…some technical data? polycount/shader setup?
Nicely done 
Hi Nicholas. Ye your right I was having some issues with the lights as unreal is great for shadow moody scenes but creating softer smoother lighting became a bit of a challenge. I have actually cheated quite a bit. For example under the stairs I had to add extra lights to lighten up the wall as it was baking out almost black. You can actually see the issue in the kitchen by the sink. The hard shadow! Unfortunately I was unable to use the same technique here as you could see the lights in the reflection as well.
In regards to a shader I used 1 master material and then created instances. Tweeting scale roughness power etc to create variation.In total I have unique textures for surface roughness, Sofa, Floor, wood pillars and wood kitchen backboard.
The poly count isn’t great as I got lazy optimising meshes. For example the plan behind the dining room table and the face sculpture take up the most and could easily be reduced by half.
Interesting…so almost unique material and tons of scalar parameter…and MIC
Good to know, I’m looking around to see if optimization on meshes is a huge problem or if some models can be imported into UE4 from Archinteriors or similar without killing UE4 
Hmmm Most classic Archinterior models are a disaster for realtime and they rarely have good UVs for textures never mind light maps (Try unwrapping 500.000 to 2.000.000 polygons 
… and if you fill a scene with them you will kill the CPU. In the UE4 marketplace is the Xoio Berlin Flat scene for download. The guy who created it comes from the classic vis background and has done little optimisation, propper uv or light mapping. So if you try and walk through it…well lets say its not much fun even though it looks great.
Im a terrible terrible human being and completely forgot to mention the Concept artist behind the scene. His name is Oskar Firek you can see his spectacular works in classic visualisation on Behance or his site “ofdesign.pl”.
CG black is always a problem. For one thing, UE4 operates in a linear gamma space, so 0.2 is closer to the actual midpoint value. This is nice for rendering lit surfaces, but not for dark scenes, or scenes containing dark and light surfaces together. I would suggest using a skylight to fill in missing reflection data, and as a softer ambient lighting solution where all other lights fail. You might need to lower the brightness of the other direct lights to get this to work. You can also render a cubemap and use the ambient cubemap post process to light up surfaces that would otherwise go straight to a black hole without it. You need to fill in missing SSR reflection data somehow: either via a skylight or ambient cubemap.
I placed the skylight and did a preview light bake. The light did soften a bit in the kitchen. But as you already mentiond the direct lights need to be brought down more and colour needs to be adjusted in one form or another.
Epic said skylights shouldn’t bake in interior environments, but my guess is that if you have windows, they will. It’s a lot nicer to use than ambient cubemaps because skylights are baked with lightmass and reveal more in areas actually lit by the sky and less in deeper shadows. You can try both and see what works better. But this is looking like one of the best architectural visualization projects I have ever seen!