Hi, my first post here! I’ve been using Blender for a few years, but recently I decided to focus on studying lighting and shading, so here it is my first (good) result with it 
First render took 5h35min to render, and the second, about 6h10min (because of DOF), in 2160x1620 and 500 samples, in a humble 550Ti. Everything was created in Blender, rendered in Cycles and compositing was done in Nuke. Lighting was only an HDR image. I plan to render an animation when I get a better hardware, but taking over 5 hours per frame, it isn’t possible. I did want to add more things to the scene, but I hit the limit of 1Gb VRAM, so I can’t put anything more haha
(Also, thanks to Iskren Marinov for the free sofa model, it’s great!)
So, I’m already moving to another project, but please tell me what you think 
Hi,
Despite the noise your renders are awesome !
The second image is photorealistic and the texture on the train is perfect. The wood floor is a little bit much shiny.
I like the contrast on the first image with the light in the background.
To reduce the noise may be you could try to light your scene with a sun lamp and some emissive objects rather than a HDR image.
I’ll decrease the glossyness of the floor and render the scene again with more samples, 500 wasn’t enough to remove the noise.
Thank you! 