Backgrounds look great, but Mario is out of place. IMO, better approach would be something like Who framed Roger Rabbit or Cool World, 2D cartoon characters with realistic world.

Ugh....when will people understand that stylization and good graphics are not mutually exclusive? Art design is not a bad thing. Don't get me wrong, neither is photo realism, but not every game needs to have it. Real life has it. I play games for escapism, I want to see things I can't see in real life!
I'm sorry, but putting Mario into photo realistic enviornements just evokes a special kind of uncanny valley. He sticks out like a sore thumb and doesn't mesh with his environments at all.
And that one stylized enviornement they did have, I'm sorry to say, looked pretty awful to me and did not showcase the engines qualities well at all. (I am aware someone presumably put a lot of effort in it and put it on the marketplace, but it's not for me :/)
Now, I'd love to see a Mario game with an artstyle in the vein Mario Kart (and yes, I'd like some AA with that, please). With all the little flourishes and polish todays technology can provide, especially with light and shadows, it would look absolutely amazing.

I just don't get it, Mario looks practically the same as in recent renditions with maybe slightly better moving and the backgrounds are just that of current gen system random places

it looks slightly more realistic, the backgrounds, but marginally so for the simple fact that (even the Mario themed section) Mario does not look to fit into his environment

he saves Mushroom Kingdom or whatever, Mario games aren't based on realism and shouldn't be perceived that way in my opinion. having Mario in a Dark Souls or Metal Gear Solid environment is useful for what reason?

just trying to 'get it'. 

the aiming for more realism I would understand more for a Zelda game or something, a game which arguably over time has attempted to mix up its art style and seems to be aiming at a slightly darker and more realistic world

I loved the cartoon world but hated him in the real world. Nintendo is about capturing your imagination and there is nothing imaginative about realism.

Mario is a bit jarring here because of the clash of art styles but if they could translate stuff like the lighting effects into an environment which matches Mario, it could look pretty good.

With that being said, I'd love to see a Zelda or Metroid game like this.

too gray, too brown

Mario on the PS4 would look nothing like this.

Is it me, or am I getting deja vu...? Maybe I would if the setting fit with Mario. Him in a place like Assassin's Creed just looks weird to me...

First minute looks whimsical and colorful, if a bit muted. The rest just clashes greatly with Mario.

That looks hideous for a Mario game even the cartoon style looks bad for it. LOL the comments on youtube. Mario looks so out of place! Now I'm not saying the work is bad just that if you make it as a Mario game it looks crap no matter how many polygons you ad or how high res the textures are or how good the lighting is.