If you ask me, the interface look and feeling is a large part of the atmosphere of the game itself. A good interface can help increase the immersion and general âfeelâ of the game - a bad interface can have the opposite effect.
If the look of the interface is coherent with the setting and look of the rest of the game, this is a great asset - if it clashes with the game and looks all too different, it can have a really bad effect on the game experience as a whole.
As an example of this, look at the inventory screen of Titan Quest and compare it with, say, the atrocity that is Two Worlds 2:
Titan Questâs inventory looks professional and coherent with the atmosphere of the rest of the game - both in terms of appearance and functionality. Two Worlds 2âs inventory looks really out of place, cluttered and unprofessional - and every time the player brings up this screen this hits him in the face.
In my opinion, the look of a gameâs interface is very important - after all, the player is going to look at it a lot, so itâs a good idea to make it look like it fits into the rest of the game. And I think Grim Dawn really nailed this so far. It looks Victorian, it looks grim. 
I do have some feedback on it, though - some things I think could be improved upon.
First off, I think the bevel effects of the item slots and especially the (what I assume is) non-activated second inventory slot (like before you got to Megara in TQ), really could be closer to the edges - in other words, look less beveled but still as strong in terms of color. As of now, it looks a little odd.
Secondly, there are some minor position issues with the text and some of the graphics - The âCombat Statsâ title is too close to the line right above it, the close button in the upper right is too far to the left, the âgoldâ counter below the item slots looks like it should be placed one pixel lower⌠things like that.
But, do understand that this is just nitpicking - I really, really like the look of the interface so far! 