You could use more color and better lighting.
Try paint wall below chair rail a darker color and use the same color in a lighter shade above the chair rail. A few same size large framed pieces of artwork would also help.
PyramidDG.com

Short of a sledge hammer it looks fine. It's well lit and un-cluttered. In this state it functions well as a passage between rooms while still being comfortable. If you clutter the walls with pictures or paintings the functions goes from passage to gallery. And as a gallery it's just too tight. Hope this helps.

it almost looks like it was wider at one time and at some point in the apartment's past someone stole a few inches of space from the hallway for the room on the right ... what is that room?

It's the kitchen where the wall narrows so no space can be reclaimed unfortunately. I like the idea of different tones, I suppose that will make it look wider? Potential for 1 pic before it narrows perhaps...